It's been raining cats and dogs in Mayville Heights. The small town's been deluged, and now the local artists' co-op is on the verge of flooding. Kathleen has been up all night helping her friends move their creations to the safety of the upstairs studio.

The artwork survives, but when controversial mask maker Jaeger Merrill is found drowned in the co-op basement, Kathleen questions whether the death was accidental. After she discovers the artist was using an assumed name, she realizes she can't actually assume anything about him. With the help of handsome detective Marcus Gordon--and Owen and Hercules's extraordinary powers of feline detection--it's up to Kathleen to unmask a killer.