Having locked herself out of her flat and spent the night sleeping in her car, Dr Caroline Todd arrives to start work at East Hampton hospital, smelling "like the inside of a taxi". Anaesthesist Guy Secretan offers her a bed at his flat - where she has an embarrassing experience in the toilet - but based on the hopes she would sleep with him, which she turns down, so he spends the night on the sofa. Elsewhere down trodden house officer Martin goes on the Internet to see if his old classmates have had worse careers than himself and hospital administrator Joanna Clore has fun with a vibrating bed.

After spending the night at Guy's flat Caroline is aware that he will try and tell everybody that they had sex. Listening to a conversation between Dr Martin Dear and his fellow doctor Boycie she learns that Guy's middle name is Valery and considers using it to blackmail him though it proves unnecessary when his affair with liaison officer Sue White is made known. Mac, the insouciant surgeon, learns that his ex-girlfriend Holly is getting married whilst Joanna feels that radiologist Alan, with whom she is having a sort of affair, is getting too clingy.

Caroline advertises for a lodger. Most of the applicants are unsuitable but she finds them preferable to Angela,the registrar,who is house-hunting. She tries to keep it from Angela but Boycie lets it slip and Angela becomes Caroline's lodger anyway. Alan feels that Joanna is falling for Lynton,the IT manager and Mac is surprised to learn that Holly,who never wanted children,is pregnant.

It is Joanna's forty-eighth birthday and she is thrilled to receive a locket, which she is told is from Lyndon. However it is actually from Alan and contains his semen. Meanwhile, Martin is also anxious to relay birthday greetings to his mother but has trouble getting through to her. Caroline and Angela find Guy's list of the most fanciable women on Green Wing and Caroline is annoyed to find Angela placed above her. She plans revenge but is thwarted when Mac and other male staff threaten to tell Guy all the unflattering things she has said about him. Martin finally gets to wish happy birthday to his mother - Joanna, who is rather anxious to keep her maternity secret.

Caroline is throwing a house-warming party and is scared that nobody will turn up. Joanna dyes her hair blonde to attract Lyndon but is abducted by Alan,who takes her to the park,where they have sex. Caroline's party actually goes very well with all the staff turning up. Administrative worker Karen makes an unsuccessful play for Martin whilst a tipsy Caroline ends up kissing Mac,Martin,Guy - and Sue White.

Whilst Caroline tries to remember what happened at her party Mac fails an interview for promotion and Martin has to sit his exams for the hundredth time. After having sex with Alan Joanna worries that she is pregnant and goes for a test but her results are confused with those of Harriet from Human Resources,who is pregnant - again. Alan is relieved when the truth is explained but Joanna dumps him anyway,causing him to steal a milk float in his anger.

Caroline is torn between her affections for both Mac and Guy and,whilst she takes an afternoon off with Guy - who is getting ready for the World Guyball semi-finals - she comes to appreciate that Mac is the man for her. This is made all the more so when Martin,too nervous to look at his exam results,is told by Guy that he has passed when in fact he has failed once more,leading to animosity between Mac and Guy. Alan seeks comfort in religion,or,more especially,Cordelia,the hospital chaplain.

The hospital holds a charity slave auction with Caroline, Lyndon, Alan and Guy among the slaves. Mac was due to enter but drops out - when he learns Sue is bidding for him - and announces that he is taking a consultancy job in Sheffield with Emmy, the physiotherapist as his new girlfriend. An embittered Sue buys Guy but makes him pretend to be Mac. Boycie buys Alan for thirty pence and they end up in bed together, whilst Joanna buys Lyndon but he dumps her after telling her he finds her disturbing. Martin buys Caroline for thirty thousand pounds but ruins their date when he believes that treating her badly will impress her.

As Mac prepares to leave with Emmy, a besotted Caroline aims to get him to stay by unmasking Emmy as a impostor. In fact it is a different person with the same name but Emmy is angry and dumps Mac,who at last ends up with Caroline. Martin,tired of Guy's bullying,opens his post only to find that they are half-brothers and that Joanna is their mother. Unaware of this Mac challenges Guy that he will not have sex with Joanna. As Guy is making a video of his session with Joanna as proof Martin comes to tell him the revelation,causing an irate Guy to stab him in the leg with Botox. Guy then takes an ambulance and drives off with Mac and Martin,ending up perched on the edge of a cliff.