Three friends, inseparable since primary school and now pushing 40, embark on the ultimate stag day. In a drunken stupor, they pay a revenge-fuelled visit to the headmaster who terrorised them many years before : little realising that the past will come back to haunt them.
Graham lands the task of clearing stacks of school files out of his old headmaster's house, but little anticipates stumbling across a secret which has been kept from him for 25 years. Meanwhile, an evening out ends in tragedy for Alan.
Terry finds consolation with Alex, and Alan vows to help him prevent the boys returning to their natural father. Molly's problems increase when her long-lost adopted son turns up.
Josh's intimacy with Becky forces Molly to reluctantly reveal the identity of his father. Meanwhile, Alan, Terry and Graham discover Peter's hanging corpse, leaving them with a dilemma over where to hide the body.