An old flame of Joan's sails back into her life and whisks her off her feet. But John Slater is seriously ill with a life threatening heart condition, as Doc Martin discovers when he insists on running tests on John. Slater wants to rekindle the love affair with Joan and sail off into the sunset with her. But Martin is anxious for Joan that she will have to nurse a very sick man. Schoolgirl Melanie Gibson, one of Port Isaac's bevy of teenage beauties, develops a crush on the doctor. He's her hero after he puts her dislocated shoulder back, and stops the agonising pain she has been suffering. Martin fears the wrath of her father when the girl keeps turning up at the surgery. She's only 15. But when Melanie's father Alan comes to visit, it is he who does the apologising for his daughter's behaviour. Martin warns Slater that he should be in hospital. If he doesn't get treatment he could be dead in six weeks. He also tells him it's inappropriate to be carrying on like a teenager with his Aunt Joan. Joan confesses she still loves John. She fell in love with him when she was still married. Now with her husband dead there's no reason for her not to be with the man she really loves. Martin tries to warn Joan not to get involved with John Slater again. He knows the prognosis is not good, but patient confidentiality prevents him telling Joan just how ill John is. Martin can also see how happy his aunt is, and learns how Joan had given up John for her husband Phil, and for Martin when he was a boy. Martin's father had refused to let his son stay with Joan while she was having the affair with John. There's romance in the air between Al and Elaine. He's always had a soft spot for her. Thinking that she has split with her boyfriend, Al tries to woo her, by downloading a special selection of music onto an expensive ipod for her.