Mark (David Mitchell) and Sophie (Olivia Colman) engaged to be married. Unfortunately Mark is having doubts, crippling doubts. Mark is invited to spend Sophie's birthday weekend down at her parents' house in the country. He is desperate to make a good impression, but foolishly invites Jeremy (Robert Webb) along, who ends up sleeping with Sophie's mother (Cheryl Campbell). Mark is livid. A weekend of country pursuits follows, during which Mark shoots a pheasant and is made to wring its neck ("there's blood all over me!") and Mark and Jeremy get involved in a spot of barn burning. Worse still, Sophie's father (Paul Clayton) hears Mark telling Jeremy that he doesn't love Sophie any more. Mark is horrified, but promises he will do the right thing and come clean to Sophie and call the wedding off. But when Mark chickens out, Sophie's father confronts him in front of the entire family. What will Mark do? Will he break Sophie's heart and tell her he no longer loves her? And will he call the wedding off? Or will he do something unspeakably cowardly?

At the annual JLB conference in Kettering, Mark's (Mitchell) boss; Johnson (Paterson Joseph), tells Mark he has to give a presentation in front of the entire board. If it goes well, Mark gets a promotion. If he fails, it is instant demotion. And Johnson takes a shine to Big Suze (Sophie Winkleman), making Jeremy (Webb) an indecent proposal: £530 to lei him sleep with his girlfriend. Jeremy can't believe it but of course, accepts. But Big Suze is horrified and immediately dumps Jeremy, and starts going out with Johnson. Jeremy is distraught. Back in Kettering, Mark's preparation for his presentation is going terribly. He is totally stressed out and has systematically abused all his workmates. To make matters worse, Johnson invites him out to a strip club, where Mark gets into an argument with a stripper.

Mark (Mitchell) is still having doubts about marrying Sophie (Olivia Carlton), so joins a gym in order to spend as much time away from her as possible. Unfortunately his personal trainer Matt (James Carlton) takes exercise extremely seriously, and wants to get Mark really, really fit. Mark can't keep up with the vigorous training programme, and almost pukes on the exercise bike. Meanwhile, Jeremy (Webb) learns that his ex-Visa-wife; the beautiful Nancy (Rachel Blanchard), has started working at the gym. Desperate to get back with her, he gets a job as a cleaner. Foolishly, Mark confides in Matt that he's been having doubts about his wedding. From then on, Matt constantly asks him about Sophie and what he is going to do about the wedding. Then, when Nancy tells Jeremy she fancies Matt, Jeremy and Mark realise they have one thing in common: they have to get rid of Matt. They hurriedly concoct a desperate plan to get Matt sacked from the gym.

David Mitchell and Robert Webb's multi-award-winning, critically acclaimed comedy continues. Jeremy (Webb) meets his hero - techno musician Russell "The Orgazoid" (Francis Magee) - and ends up working as his handyman. But Mark (Mitchell) gets suspicious, as Jeremy's job seems to consist of making Russell smoothies from a smoothie maker and swimming in his pool. Mark thinks there must be a catch: "He's going to sell your organs on the internet." And Mark goes to a school reunion, and considers embarking on an illicit affair with a girl he used to fancy, Sally Slater (Liz May Brice).

David Mitchell and Robert Webb's multi-award-winning, critically acclaimed comedy continues. As Mark's (Mitchell) best man. Jeremy has organised a stag weekend. This consists of Mark and Jeremy (Webb) on a canal boat on the Shropshire Union Canal. Unfortunately, it's cold; there's nothing to do, and Jeremy is instantly bored. But things soon spice up when Jeremy meets a new girl, then does something unspeakable to her pet dog. Meanwhile Mark gets offered an exciting new job in India. Could this be his way out of his impending marriage to Sophie (Olivia Co man)?

Series finale of David Mitchell and Robert Webb's multi-award-winning, critically acclaimed comedy. It is the big day: Mark (Mitchell) is getting married to Sophie (Olivia Colman). Mark and his best man, Jeremy (Webb), set off in the car to the church, with a very hungover Super Hans (Matt King) in the back. Mark wrestles with his crippling doubts throughout: but will he go through with the wedding?