Will (Simon Bird), Neil (Blake Harrison), and Jay (James Buckley) are struggling after their relationships crumble, leaving Simon (Joe Thomas) eager to end things with his overly clingy girlfriend, Lucy (Tamla Kari). As Will and Simon dive into university life, Neil has taken a job at a bank, and Jay is enjoying an adventurous gap year in Australia. He entices his friends with tales of being a top DJ, partying in a luxurious mansion, and “enjoying” life with multiple partners, persuading them to join him for a holiday.
Upon their arrival, the friends are shocked to discover that Jay is merely working as a toilet attendant and living in a tent in his uncle's garden. Meanwhile, at the club, Will reconnects with an old friend, Katie (Emily Berrington), who is backpacking. Influenced by Katie, Will decides to embrace a new adventure. However, Simon's attempt to break up with Lucy through a Skype call hilariously backfires, resulting in Lucy mistakenly believing that Simon has proposed to her.
The group's journey takes them to Byron Bay, where they hop into a car inspired by Peter Andre, driven by Will’s newfound motivation to track Katie down. Unfortunately, Will's attempts at fitting in with the backpackers lead to embarrassment as they perceive him as a mere tourist. During a heartfelt Skype call with his mother, Will realizes someone else is staying at their house, which she quickly denies.
Their escapade continues at a water park where Jay seeks out his ex-girlfriend, Jane (Lydia Rose Bewley). After learning that Jane is in the remote Birdsville, the boys decide to embark on a journey to find her. Complicating matters, Will grapples with his feelings for Katie while facing the harsh realities of the "spiritual" backpacker lifestyle. As tensions rise, Katie's infidelities lead to Will's ignoble outburst, pushing her towards another man, Ben (Freddie Stroma).
When desperation sets in and their car runs out of petrol in the arid desert, the boys struggle to find help. In a dire moment, Simon resorts to drinking Neil's urine, only for Neil to hilariously misfire. Together, they hold hands, confronting the possibility of death before being hilariously rescued just hours later by Jane and her colleagues. Though touched by Jay's efforts to rekindle their romance, Jane ultimately decides not to take him back.
Returning to Jay's uncle’s house, the boys are stunned to find their parents have come looking for them, including their former head teacher, Mr. Gilbert (Greg Davies), who is now dating Will’s mother (Belinda Stewart-Wilson), much to Will's dismay but his friends' amusement. In a moment of newfound courage, Jay confronts his uncle about his crude remarks towards Jane, leading to a comical brawl between family members. After all this chaos, Lucy breaks up with Simon through Skype, revealing she’s now with his university best friend, Pete. To Simon's surprise, he cheers and hangs up abruptly.
As the credits roll, the group decides to embark on another adventure to Vietnam, returning home only to discover that Will’s mother and Mr. Gilbert are now engaged. In a fit of disbelief, Will tries to escape but is hilariously apprehended by security before he can run away from it all.
