In the centre of New York stands the city's most notorious library. It has a history of mysterious disappearances and freak accidents. But tonight, it opens its doors to welcome a group of strangers for an exclusive after-hours tour. The famous author. The journalist. The professor. The bookseller. The architect.

They are here to see a legendary book - one of the most valuable in the world. But each visitor also has other, more sinister reasons, for being in the library after dark. As the tour takes them deeper into the building, one of the guests meets a gruesome, inexplicable end - and the others realise they are living on borrowed time. The search for the murderer forces them to confront awful truths about themselves and decide which secrets are worth dying - or killing - to keep.