Sounds of jazz, blues, the twist and the tango drift through a city’s streets as coupled cats cavort on a Saturday night. The cavalier kitties hop and hoof it across rooftops, multiplying in twos per couplet in Stutson’s poem. Cool as cucumbers, the swaying pusses raptly dance, enchanting in their indifference to the sleeping metropolis. Klassen’s muted color palette contains the warm glow of a cityscape—festive stringed lights, a brilliant marquee, lit windows sprinkled among darkened frames. His atmospheric illustrations have a Matisse-like papercut construction, and the digitally collaged artwork is lyrical with flowing compositions and lovely textural layering. As the story is about music and improvisation, the illustrator’s use of shape and texture is similarly spontaneous. The weakness is in the text’s integration with the illustrations, and it’s unclear if the author intended certain lines to be broken apart or if the design demanded it. Playful and silly, the text takes readers from two to 20 cats; quibble aside, a comely counting book. (Picture book. 4-8)