Kiss of the Mermaid (Mercer Mayer's Critters of the Night)

Illustrated in full color. The wicked sea witch has turned the family of Mara the mermaid into giant chess pieces and hidden them in a deep-sea cave. Thistle Howl wants to help, so Mara turns Thistle into a mermaid. Now they can both swim to the rescue, except there's one catch: the sea witch needs two more chess pieces--just the size of Thistle and Mara! Will the heroic mermaids sink or swim?