London, 1865. There are many mysteries in this world that are yet to be resolved. Some of them, man was not meant to know . . .

Scientist, inventor and occasional sleuth, Horatio Lyle, is a man of science - a man of reason. As such, he does not care for the Tseiqin and the strange, mystical enigma they represent. But when news reaches him of a plot to remove them - through the simple expedient of mass murder! - well . . . that presents a problem for a man of moral fortitude. A decent man. A man like Horatio Lyle . . .

Leading his young friends, Tess and Thomas, and his faithful hound, Tate, into a series of the most appalling dangers, Lyle leaps to the rescue of his mortal enemies. But when the dust clears and the menace has been confronted, there remains one rather pressing question for occasional Special Constable Horatio Lyle: who's going to rescue him . . . ?