As a library cat, Dupin receives the attention and admiration of the public, as one would expect. He allows his human, librarian Penny Copper, to take care of the mundane business of running the library while he reaps the benefits.

Until a body turns up in the large green metal book return in front of the building. Now Dupin must turn his razor intellect to the problem of the murder—or risk further disruption of his routines. A hint here and a clue there should give Penny all the help she needs to solve the murders of the Reed Moore Library.