The crooked hinge.

I really enjoyed this mystery novel, though I found the ending a little ridiculous. I found it quick and engaging, if not a quite tangled story. Sir John Farnleigh is a wealthy man with an inherited estate and a good life, until another man shows up claiming to be the real John Farnleigh, and accuses the former of being an imposter. His former childhood tutor has the fingerprints of the real John, and subjects the two of them to a fingerprint test, but before the results can be discovered, the fingerprint evidence is stolen and one of the John Farnleighs is found with his throat slashed. But which John Farnleigh is dead — the real one or the imposter? And was it a guilty suicide or a malicious murder?