Paramedic Mark Poole is subletting his aunt's flat as he recovers from a work-related breakdown. He fills his days with helping the neighbour with her garden, doing odd jobs, trying not to think about the call that resulted in his having to take a leave of absence. When he hears a voice that no one else seems to hear, sees things that no one else seems to notice, the house next door assumes a darker significance and he determines to find out what's going on, who it is that needs his help?

His search opens the floodgates to more strange occurrences, and soon Mark is fighting for his life—or his sanity, if he's wrong, as his friends insist he is.