At the Manchester Centre for Sexual Health, the staff treat 22-year-old Kervin, who has some issues to address after a one night stand leaves him with more than just a smile on his face. 17-year-old Courtney shocks her mum with lurid confessions of unprotected encounters in the park, while ladies man Joe discovers if putting it about has landed him in it.

20-year-old gay porn star Lloyd has a double dose of bad news from the clinic, 31-year-old Heidi is terrified that a bout of chlamydia as a teenager has left her infertile, and housemates Martin and Marissa can't agree who should carry the can for an outbreak of scabies.

John comes into the clinic hoping he won't be diagnosed with chlamydia for an astonishing fourth time, clinic staff provide sexual health care for the inmates of maximum security jail HMP Manchester and, after a drunken one night stand, 26-year-old student Ben tries to persuade his girlfriend to lift a sex ban by proving he's still STI-free.

Twenty-year-old Gary finds out the hard way that it's not just STIs condoms are designed to prevent. Pre-op transsexual Jasmine hopes her high-risk sexploits don't jeopardise her life-changing operation.

In Leeds, 19-year-old Jack has been enjoying the sexual benefits of an open relationship, but perhaps a little too much. In Exeter, Kev has been told that one of his exes might have given him chlamydia, Tilly's worried about a potential unplanned pregnancy and free spirit Chantelle can't see why the risk of STIs should stop her experimenting sexually.

In Leeds, 23-year-old Krista and 20-year-old Emma have come to the clinic after enjoying the benefits of recently becoming single, while Geoff is facing the prospect of a third bout of chlamydia. In Exeter, Josh has had chlamydia before, but has he learnt from past mistakes? Ash worries that he could have passed on an STI to new boyfriend Jazz.

In Leeds, 18-year-old ladies man Ollie has been enjoying himself, mostly without protection. 20-year-old Heather has been suffering with genital warts. In Exeter, farmer Greg is suffering with pain down below and his new girlfriend won't sleep with him until staff have got to the bottom of it

In Leeds, Anne-Marie and Nathan are having a check-up before they get married. Also visiting the clinic is transgender beauty therapist Sasha, who is concerned that her sexual health may stand in the way of her gender reassignment surgery. In Exeter, farmers Olly and Dan are heading for their first ever sexual health check-ups after enjoying wild nights at young farmers' discos.

In Exeter, 21-year-old Scott has been partying so hard he can't remember who he's slept with. And will it be double STI trouble for brothers Robbie and Tom after a season of festival fun? In Leeds, 25-year-old Chloe is facing the prospect of her second STI, while ex-army recruit Carl has heard rumours that an ex may have given him chlamydia.

Best friends Eve and Joel are worried that ex-partners may have left them with more than just memories and decide to come to the clinic to find out for sure. Likely lad Tony wants to overcome his fear of getting tested to find out if never using a condom has left him with an STI.