Maria Black, the woman's school headmistress who doubles as a detective, is invited to attend the engagement celebrations of an ex-pupil of her college. There she finds herself involved in the mysterious suicide of the prospective bridegroom, Keith Robinson. All the circumstances—death by hanging in a locked cellar—support the idea that Keith took his own life. The coroner, too, is satisfied that such was the case—but certain peculiar factors of the death lead "Black Maria" to think otherwise. Aided by her American Bowery companion, "Pulp" Martin, Maria sets out to prove how Keith really died—and in doing so uncovers an ingenious plan of cold-blooded murder. But who is the killer—and why was Keith murdered?

This fifth—and final—novel in the Black Maria series is a classic "locked-room" crime novel, one that will leave the reader guessing right up to the last page!