Three couples attempt to plan their attendance at a philharmonic orchestral concert. Barney and Cathy argue about Barney's refusal to go to the performance to which they have tickets. Evan is also refusing to attend with Fiona as he prefers to to watch the football instead, and finds the idea of watching an orchestra "poncy". Alice is also enjoying some alone time with older partner David being unwell and held up in bed, while lamenting his age, with Alice hoping he is unwell enough to attend the concert and looking forward to going without him. As the event draws closer, David takes to dying his hair in an attempt to look younger, while Barney and Evan get drunk in the pub as Evan attempts to convince Evan to attend, as Cathy panics believing that Barney is interested in Alice, being determined to keep them apart.
2. Weekend Away
Cathy is arguing with Barney about wanting a weekend away in the country with Evan and Fiona; staying at David's cabin. Alice meanwhile has "lost" her daughter Maddie, only to discover that David has dropped her off at her grandmothers so the two can spend a weekend alone together with "quality time". With the two couples about to set off, Cathy and Fiona compete over their wardrobes and how they look, while Barney and Evan take part in competitive packing of the car before the two couples end up in heavy traffic as Evan constantly contradicts the Satnav before promptly getting stuck. Eventually arriving, Alice and David also turn up to fix the boiler where both Barney and Alice contemplate revealing their feelings to each other again. As the night approaches, the three couples eventually settle into a discussion which ends up men vs women which causes fractures.
Evan is organising a school fundraiser event, and Cathy and Barney getting into an argument about whether they attend. Barney eventually loses, leading to them joining Fiona and Evan. Evan meanwhile has been spending some time with Miss Pringle, and has to get Barney to go along with his lie. David and Alice meanwhile are at home, with David struggling to work out the difference between Tess Daly and Cat Deeley, while Alice continues to lament marrying an older man. Fiona and Cathy spend their time talking about their relationships, with Fiona admitting to straying as retaliation, and also manages to convince Fiona to start looking around. David is also planning on buying a jazzy suit, to improve his appearance, as Barney looks forward to spending some time with Alice who has some French lessons up for auction as part of the fundraiser. However, the best laid plans don't always work out.
Barney is initially refusing to attend a barbecue at David and Alice's, while Cathy is intent on the pair of them going. He eventually agrees to go at the thought of Alice being there. Fiona is also upset while going through Evans's social media photo album and realising there are no good pictures of her. David also has a similar problem, except Alice has no pictures of him at all. At the pub, Evan and Barney discuss their relationships at the pub, with Barney irritated that his emailing Alice is upsetting to Cathy. He also has to deal with David later on who is attempting to "friend" him with an invite to lunch. Fiona also has to deal with Evan publishing a video of her snoring on the internet. At the barbecue, Fiona attempts to put Alice off Barney, while David attempts to dissuade Barney from Alice.
5. Two Parties
Cathy is attempting to persuade Barney to have an anniversary party, though Barney quickly agrees rather than spend time alone with her. Evan is in the bad books after giving Fiona cash for her birthday present, rather than the surprise she really wanted. Alice meanwhile is dreading going back home to David, and contemplates how much longer she can take his "love". Barney takes to inviting Evan to the party for support. However, problems occur when Alice's birthday party is also due on the same day resulting in everybody committing to go to the anniversary celebration. David arranges with Barney to team up on the parties, resulting in an angry Cathy. He also gets himself in further bother when he follows Alice into Marks & Spencer and claims to be buying underwear for his wife. Barney gives a speech to his wife to honour their anniversary, but ends up accidentally saying that he loves Alice.
Not wanting to go to the garden centre, Barney is eventually persuaded instead to go to Filey by Cathy to rekindle their marriage. Evan meanwhile has to handle Fiona who is panicking about being stuck in the car, and contemplates the power of leaving her stuck in the car. Alice remains bored to death with David, who is making plans to visit a farmers market while she is on the toilet - hiding from him. Out for a walk with Evan, Barney decides he is leaving Cathy for Alice. However, Evan is dumbfounded at the idea with Barney not having "tried out Alice". At lunch, David also takes to talking to Fiona about his belief that Alice doesn't love him any more. With two relationships in turmoil, the four end up at the same restaurant to talk out their problems, while Evan and Fiona panic at the impact on their own relationship.
Evan thinks he has overdone it this time by criticising the amount of time it takes to put on her vast quantities of makeup, and takes to talking to Barney about the situation, now that she isn't talking. With a wedding due for friend Amanda, Barney, Evan, Cathy and Fiona are due to attend. Meanwhile, Alice and David are also going though Alice has to contend with her dry-clean only dress being ruined. Evan, back at home is refusing to concede in his battle with Fiona and does not apologise, and continues to upset Fiona when he doesn't remember that the wedding venue is the same as the one they were married at. Barney also takes to upsetting Cathy when he suggests that she wasn't skinny when they met. At the event, relations between the men and women don't get much better, until they each decide to dance with the other. The night doesn't go to plan for Barney however, who gets stuck in a bag when he tries to rekindle things.
Alice is upset when she discovers friend Philip is dead of a heart attack. David however takes advantage of the situation as she wants some physical comfort. Meanwhile, Evan finds he now owns a dog she has named Mr. Barker which Fiona has brought home, despite him not liking dogs. Barney and Cathy also discover that Philip has died, though Barney shows little concern due to it being an expected death, with Philip's poor physical condition. The pair end up arguing about whether Barney would be upset if Cathy died first, though he spends more time contemplating his future life. Evan and Fiona have to adjust their life to prevent Mr. Barker from barking, while Cathy worries about being outdone at the funeral by Alice who Barney meets while shopping. David is also planning on giving the eulogy for Philip, though ends up with laryngitis with Barney stepping in to take over, and use the opportunity to work his way into bed with Alice.
Cathy thinks she is pregnant, and Barney's first questions are to ask her whether she isn't too old and whether it is his. Despite also waiting on telling anybody, it isn't long until Evan and Fiona also know, which leads to a discussion about him having a vasectomy. When he refuses, she suggests that sex is off the table until he gets fixed. David and Alice have also heard the news, with a melancholy Alice contemplating being unable to have any more children. Evan is now having gone without for three weeks, which leads to him capitulating and agreeing to an operation. David and Alice look at adoption but suffer a setback through official routes, so decide to take a look at websites offering less-than-legal methods. Getting cold feet about the vasectomy, Evan takes to faking it with Barney's help. As Barney comes to terms with a new child, Cathy also discovers that she isn't pregnant. However, Evan's poor decision-making comes to haunt him.
4. David's Villa
Cathy is on a diet which is leaving her miserable. The couples attend Alice's birthday party where David has purchased her a villa in Italy for the pair to retire to. The three couples plan to head out to the villa, where the men intend on completing renovations that are required, while the women make plans to enjoy the sun. David however plots to "forget" Alice's passport, to prevent her from getting too close to Barney, which requires her to catch a separate flight with Cathy and Fiona. Landing in Italy, Barney and Evan find themselves in the middle of nowhere, with Barney's first job being to start digging a hole for the pool and Evan struggling with a shortage of alcohol. Barney ends up getting sunburnt by falling asleep in the sun, while Cathy manages to get into her old jeans. Fiona however saves the day by bringing a large stash of drink. Barney's hope of seeing Alice in a bikini however is stolen from him when she turns up poolside in a burkini.
Alice has bought tickets to Glastonbury, though David is less than thrilled at the prospect. Evan meanwhile finds out that his anecdote's are considered boring by Fiona, and have been since they got married. Cathy also wants to know why Barney hasn't installed a tracking app on his phone for her. Evan, Fiona, Barney, and Cathy have also been invited to Glastonbury, though the festival coincides with the birthday of Cathy's father which will involve a weekend diversion to a care home. David however is pleased at the thought of a tracking app for Alice. At Cathy's dads birthday, Barney has to contend with a senile elderly lady who thinks he's her husband, while he misses out on the mud sliding going on at the festival. Heading to their bed and breakfast, Barney and Cathy find that neither one has booked a room, while Evan has to deal with David driving him insane, and Fiona broaches the topic of Barney with Alice.
6. Date Night
David is telling Alice about his day filled with busy meetings, but actually doesn't have a clue about what he does. She also sets about plans for herself for going back to work with a new business idea, though David is against it. Barney meanwhile is attempting to make a voice controlled text messenger working, and also has to get out of "date night" but still ends up involved in one alongside Evan and Fiona. David and Alice also end up tagging along and the couples end up visiting a French cinema which proves a big hit with Evan. David ends up offending both Fiona and Cathy with a sexist jibe, while Alice's business idea ends up getting rejected by him who instead suggests she work for him as a personal assistant. Cathy and Fiona set about proving to their husbands they can talk about anything other than men, while Alice quickly learns David's business and sets about modernising it, much to his reluctance.
Steve, Cathy's brother, has sent his usual Christmas letter, with him and his family also being invited by Cathy to dinner. Meanwhile, Evan has bought Fiona a plastic surgery voucher as his gift. David is updating his Christmas card list while Barney has set plans in motion to get Steve not to come by claiming he has had a small heart attack. David also plans a spontaneous photograph with him dressed as Santa and Alice in a skimpy outfit as the helper, which will their Christmas card photo this year. Cathy and Fiona get to talking about the worst present they've received, and Cathy finds out that Barney has referred to her breasts the "National Geographics". Fiona has a bad reaction to her lip improvements, though takes to showing them off in the pub anyway. Cathy also tries to tempt Barney into looking at the picture. The couples end up going sledging, with Barney ending up crashing into a tree.
Cathy and Fiona are going away for the weekend with Barney and Evan both anticipating their leaving, with Evan packing the kids off to their grandma. Alice wonders if David is feeling okay, and wonders if he is hiding something from her. David is also due to head away for a stint in the hospital due to issues with his prostate, though Alice has to bear the thought of packing his teddy bear - Lord Teddington. Barney and Evan take to the pub to celebrate their freedom, while Cathy refuses to get naked in the sauna with Fiona due to being self-conscious about her figure. Barney and Alice catch up with each other, and soon find them planning on starting the affair, by checking into the nearby Travelodge, though things don't exactly go to plan. At the sauna, Fiona tries to encourage Cathy to get some confidence by approaching a man.
1. The Third Way
Heading to Evan's, Barney admits to Cathy that he is getting a little bored of seeing them so often. The discussion leads to Cathy signing them up for Scottish country dancing lessons. Evan meanwhile has broken his coccyx after a fall from a stepladder leaving him to sit naked in a blow-up ring. David and Alice meanwhile are watching The Night Manager in which David's memory appears to be going, with her suggesting he have an Alzheimer's test. At Evan's, it comes to light that Fiona fancies Sam Allardyce after Barney discusses his "third way" of living idea with Cathy - which involves sleeping with someone unattainable and the partner not being able to object. At the pub, Fiona is chatted up for a man who is similar looking and also called Evan, while David is doing his best to keep his mind sharp. Evan discovers Fiona's attraction to his double, and confronts him, which leads to a fight in which Barney also breaks his coccyx - and David appearing mentally unwell.
The three couples are having dreams and nightmares about their relationship situations. Barney is confronted by Cathy about him shouting out Alice's name in his dream, and suggests that they go to couples therapy. He also discovers that Evan and Fiona are in therapy whose sessions have devolved into arguing about whose fault it was they were late to the session. Attending the session, Cathy refuses to reveal her honest opinion, while Barney wonders how long it will be before he is blamed by the therapist. David and Alice also take to visiting a therapist, though he initially believes that Alice is David's daughter and takes a fancy to Alice himself. Meanwhile, back at home, Barney has to cope with his fathers constant phone calls with medical complaints. However, despite initially seeming to go well, all the couples end up leaving the therapist, who himself also decides to quit the profession.
Discussion between Barney and Cathy turns to who is the most attractive, which leads Cathy to propose them both joining Tinder to see who gets the most attention, with Evan also deciding to join and compete. David meanwhile finds out that Alice's art class is painting a naked Italian Olympian. Alice brings home her painting of her model and places it in the bedroom, though David tries to find positives. Evan's attempts to win the competition on Tinder also fail when he matches with an odd Ukrainian woman, which leads them to compete by setting up profiles on Grindr. David takes to modelling himself at the life drawing class, while Barney discovers that he has interest from Gary. Cathy and Fiona also decide to compete on who would be the most attractive lesbian, as David sets about showcasing the painting of himself at an exhibition.
4. Cathy's Dad
Cathy has returned from visiting her dad, Dennis, in a care home which has left her feeling depressed, and suggesting that he should come and live with them. He has also developed a condition where the wrong words come out of his mouth. Fiona meanwhile is recovering after a throat operation which Evan hopes will keep her quiet for six weeks. Alice is off watching Maddie practice for a minor role in a school play, though David insists that she be given one of the lead parts to boost her confidence. Barney is given the job of taking Dennis out for a walk, and upon meeting Alice, realises that he can use the ailing old man to seem caring. Fiona's voice has begun to return, though she continues to use a text-to-speech device which they use while having sex, while David and Alice are arguing about how to bring up Maddie which results in Alice hoping she fails during her play to prove her right.
Cathy suggests to Barney that they make cutbacks to their budget, who has pinned his hopes on an academic book of his bringing in lots of money. Cathy instead has the idea of renting their spare room out using AirBNB. Evan and Fiona are planning on going out, though take to arguing about who has the house keys which result in them not leaving the house. David also decides to write a book since Barney has, and takes to adapting Alice in Wonderland with an erotic twist. Barney also signs up as an Uber driver as a ruse to pick up Alice when she books one. Evan takes to checking in to Barney and Cathy's when he has a big argument with Fiona, though the two end up making up repeatedly in their temporary lodgings. Barney meanwhile makes another Uber pickup in attempt to collect Alice, though finds it is David who is heading off to see a publisher. Evan ends up renting the room permanently to improve his sex life, while Alice indicates she is leaving David whose books has proved popular.
Barney has woken up with the urge to apologise, which Cathy suggests is an ulterior motive. Alice meanwhile has finished her walk and has been thinking about how as a couple, they never talk properly and David is too controlling. Evan takes to gambling to try to get himself out of a financial hole while Fiona ponders starting her own business with a bar that only offers board games and cereal. Alice ups the ante with David, and threatens to leave if he doesn't change his way. Barney has also managed to get over his obsession with her, when he finds out what she really felt about their previous close encounter. Fiona opens the shop, despite Evan's scepticism, which ends up being a surprise hit. Barney, Evan and David end up playing poker though end up competing for Alice and Evan admits his monetary problems to Fiona. The situation causes rifts in each of the marriages with the men and women deciding to stay with each other.