Sean is horrified to discover that his best mate Dylan has a secret plan that threatens to derail their 'lads holiday' to China. Things start looking up with they meet two American girls, Ashley and May, and middle-aged hanger-on Greg. But, when old tensions re-surface and create carnage at a music festival on the Great Wall, Sean suddenly finds himself way out of his depth.
May has to go to a cousin's wedding in Hangzhou, and Ashley insists that Greg and Dylan tag along. The family reunion is not what any of them imagined, as Ashley becomes the unlikely centre of attention. Greg explores a niche business opportunity in Shanghai with Dylan's help. Sean tries to join up with the others by hitching a lift with a pair of creepy newlyweds who think he might be just the thing they need to spice things up.
May and Ashley decide to do some 'good' by volunteering at an orphanage in rural Vietnam, but May is surprised to discover that volunteering actually involves hard work... Dylan and Sean claim to be travel writers to blag a top room in a luxury hotel. Sean tries to heat things up between him and Ashley with unexpected results. Meanwhile Greg tries to move on from his ex-wife by pursuing a nurse at the orphanage.
Greg leads the gang to a legendary Full Moon Party in Thailand, but an unexpected face from the past turns up and threatens to ruin everyone's fun. When May gets a tummy bug, Ashley resorts to desperate measures to ensure May's sickness doesn't affect her and Sean's wild party plans. A moment of unexpected romance provokes Dylan into doing something rash.
The gang go on a trek and get lost in the jungle. Lauren discovers the truth about Dylan and Ashley, Sean receives some unexpected romantic attention, while Ashley bonds with an off-beat French trekker. Greg gets bitten by a tick, temporarily loses his hearing and gets a bit shouty. With tensions bubbling over, and Greg in emotional meltdown, it's make or break time for the gang.
The gang head to Kuala Lumpur to visit Greg's old school friend Jotty. Greg gets a job opportunity too good to refuse. May's decision to sow her wild oats backfires, and Ashley receives some bad news from college. Dylan tries to save his friendship with Sean, while Greg and Jotty face off in an epic, high-stakes squash match.
The gang sign up to be extras in a Malaysian zombie film and Greg finally gets to fulfil his childhood dream of becoming a policeman. May gets an unexpected opportunity to reconnect with her Chinese roots, while the love triangle between Sean, Ashley and Dylan reaches an explosive climax.
Dylan is taken to a Buddhist Monastery after a surprise meeting with Sam Bevan, the vengeful travel writer he impersonated in Vietnam. While attempting to liberate Dylan from certain brainwashing, May is subjected to a surprise visit from her mother, Greg looks for some new travelling companions and Ashley and Sean confront their feelings with potentially disastrous consequences for everyone.
