A month into a six month prison sentence for dealing mushrooms and weed, 28-year-old techno DJ Alex King is offered a way out. So long as he can provide a home address, he can see out the rest of his sentence under home detention. But there's a problem. Before he was arrested, Alex had crashed at his best mate Dave's house for six months and had outstayed his welcome by five. Desperate to get out of prison, Alex tells his probation officer that he still lives at his last known address: a London flat belonging to his ex-girlfriend, 27-year-old masseuse Karen. Alex's probation officer is too busy to check that this is true: as long as the place has four walls and electricity that's good enough for him. Karen is horrified when she gets back from the shops and finds Alex under house arrest in her flat, especially as she's still hurt that Alex dumped her at a party.