With Mark and Sophie engaged, the season follows their fraught wedding preparations, growing doubts about the future, and a disastrously awkward ceremony, as Jeremy’s own escapades add to the chaos in typical cringe‑comedy fashion.
Mark continues to dread the impending doom of his wedding day, still questioning his actions from the previous season. Both Mark and Jeremy meet Sophie's parents and brother- leading to disaster with arson, sex with a parent and drunken arguments.
Johnson returns, immediately taking a shine to Big Suze, proposing a deal involving her to Jeremy. Mark is caught up in Johnson's "Project Zeus" with his reputation at the workplace hanging in the balance. Geoff makes his first appearance of the season, and Sophie spends some alone time with Jeremy in the hotel room.
In order to avoid spending time with Sophie, Mark gets a gym membership. Whilst there he discovers that Jeremy's ex-wife Nancy is working there. Mark tells Jeremy who then becomes desperate to get back together with her. He decides to take a job as a cleaner at the gym and sets about stopping her from dating Mark's personal trainer Matt.
Jeremy meets his hero, techno musician Russell "The Orgazoid". He ends up working as his handyman, which leads Mark to become suspicious, as it seems that Jeremy's job consists of making smoothies for him. Meanwhile Mark meets Sally at his school reunion, one the few girls who actually ever liked him. It turns out that she has married one of Mark's childhood tormentors, Foz. Mark decides to try and seduce Sally whilst Sophie is away on a business trip.
Jeremy takes Mark on a stag weekend, with a rented canal boat. There, they meet two sisters, Aurora and Lucy, and their father. Jeremy falls in love with Aurora, whilst Lucy becomes sexually attracted to Mark. The father offers Mark a job in India, a way out of his impending marriage to Sophie, whilst Jeremy accidentally kills, and then eats a bit of Aurora's dog.
It's Mark's wedding day. He is torn about whether he should go through with it or not. Jeremy discourages him but Mark continues. On the way to the reception, Sophie breaks down and runs away. Jeremy comforts Mark as the 'El Dude Brothers' are reunited.
