Will (Simon Bird), Neil (Blake Harrison) and Jay's (James Buckley) girlfriends have all broken up with them since the events of the last film, and Simon (Joe Thomas) wants to break-up with his girlfriend, Lucy (Tamla Kari), who has become too clingy. Will and Simon are at university, Neil is working in a bank and Jay is taking a gap year in Australia. He emails the others, claiming that he is now a top DJ, runs a huge night club, lives in a luxury mansion and has daily sex with multiple partners, convincing them to join him there for a holiday.Once they arrive at the club they find Jay in fact only works as a toilet attendant. While at the club, Will meets Katie (Emily Berrington), an old friend who is backpacking, and she convinces him to join her. Jay in fact lives in a tent in the front garden of his uncle's house; there Simon attempts to break-up with Lucy via a Skype call. Jay's uncle's interferes and tricks Lucy into thinking Simon asked her to marry him.The four main characters drive to Byron Bay, along with the backpackers The next day the four travel to a youth hostel in Byron Bay in a Peter Andre-inspired car, as Will wants to follow Katie there. He attempts to become friends with one of the backpackers, Ben, but he is looked down upon because it is clear that he is a tourist and not a "traveller". After arriving, Will Skypes his mother and notices that someone else is staying at their house, which she tries to deny.The following day, the boys and the backpackers visit a water park, where Jay intends to find his ex-girlfriend, Jane (Lydia Rose Bewley). The park staff tell Jay that Jane has found a new job in the vast outback, but they don't know specifically where he can find her. Lucy tells Simon via Skype that Jane is working on a stud farm in the remote settlement of Birdsville, and the boys intend to drive there. Will however decides to follow Katie instead. He struggles to fit in with the 'spiritual' activities of the travellers and discovers that Katie is seeing multiple people at once, launching him into one of his foul-mouthed tirades towards them, which leads Katie into having sex with Ben (Freddie Stroma).The next day Will leaves the hostel and by plane travels to reunite with his friends. While driving to Jane's workplace, their car runs out of petrol in the middle of the desert and the four unsuccessfully attempt to find a source of water or help. Desperately dehydrated, Simon resorts to drinking Neil's urine, but Neil misses and urinates over his face. The group hold hands together as they realise that they will most likely die, but are rescued by Jane and her co-workers. It is revealed they have only been stranded for a couple of hours. Jane realises how far Jay came to win her over again, and although she is touched by the gesture, she does not take him back.Back at Jay's uncle's house, the boys find that their parents have travelled to find them after hearing of their 'near-death' experience. The boys are shocked to find Mr Gilbert (Greg Davies) (their old head of sixth form and Will's nemesis) there too, and Will's mother (Belinda Stewart-Wilson) announces that she and Gilbert are in a relationship, to the abject horror of Will and amusement of the other three friends. Meanwhile, Jay finally shows some backbone and slaps his uncle for insulting Jane's weight, instigating a fight between his uncle and father. Over Skype, Lucy breaks-up with Simon because she is now in a relationship with his university 'best friend' Pete, which Simon responds to by cheering and abruptly hanging-up on her.The four boys decide to travel to Vietnam in a montage during the film's credits. As they return to England, Will's mother reveals that she and Gilbert are engaged and he attempts to run away from them back towards their plane, but is wrestled to the ground by security.