Dylan must contact all the girls he has slept with to inform them he has chlamydia. He casts his mind back to Abigail and a flashback reveals a defining moment he'd tried to forget...

In a flashback to 18 months ago, Luke is enjoying the best sex of his life with psychology student Cleo, but he's keen to avoid deep conversation in case she realises that he's actually quite shallow.

In a flashback to 10 months earlier, Luke drags Dylan and Evie to a posh party in the country. Luke is desperate to sleep with his childhood crush Ilona, who's on his 'things to do before I die' list.

In a flashback to three years earlier, it's Evie's birthday and she plans to tell Dylan about her feelings for him over a quiet dinner, but the evening gets hijacked by their friends.

In a flashback to four years earlier, Dylan panics that he's in a serious relationship with Bethany, while Luke has trouble with his new boss Diana.

Dylan sets about tracking down Phoebe who hasn't returned any of his messages. This prompts a flashback to six years ago when the gang are at a pub quiz.