Hag's Nook, first published in 1933, is a detective novel by John Dickson Carr and the first to feature his series detective Gideon Fell.

Tad Rampole is a young American traveling in England who, in a chance encounter on a railway platform, meets and falls in love with Dorothy Starberth. Rampole has a letter of introduction to Dr. Gideon Fell and both soon become involved in the affairs of the Starberth family. The family has a long history as having been the governors of Chatterham Prison and, in connection with that post, there is also a tradition that the "Starberths die of broken necks". Chatterham is now abandoned and inhabited only by rats, but the eldest son and heir to the Starberth family must spend the evening of his 25th birthday there, as directed by an ancestral will.