Dr Katherine Lewis is a dentist passionate about her profession, but not exactly a people person. After a road accident she finds herself in Limbo, and is allocated the job of Tooth Fairy while she waits her turn for Judgement. She is not impressed with the costume she has to wear, or having to deal with kids. The flying is fun, though. And very soon, the strict "don't interfere" rule is not so much broken, as irretrievably shattered.