Mystery of the Midnight Menance — Nancy Garden

There's evil under the full moon...
Armed with his dogeared copy of The Complete Sherlock Holmes, Brian puzzles over a series of curious clues; two mangled dead pigeons, a half-eaten rat, eerie howls in the night, a menacing doglike creature prowling the apartment house roof. The attacks continue, growing in ferocity and intensity -- always beneath the full moon. Brian and his visiting monster hunting friends, Darcy and Numbles are convinced that something supernatural is on the prowl! What would Sherlock do? Human lives are at stake.