Kiss of the Mermaid (Mercer Mayer's Critters of the Night / Step into Reading, Step 3)

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?