The annual classroom exchange of valentines is the backdrop for this engaging story about retaliation. Gilbert remembers how hurt he felt when Lewis tweaked his nose and when Margaret made fun of his glasses. So when he's faced with 15 blank valentine cards, each one waiting for a poem, he decides to hurt them in return. ``Roses are red, you wet your bed. I think that you have rocks in your head,'' goes to Margaret (he signs it ``Lewis''), while Lewis's card carries the sentiments of the book's title (Gilbert signs that one ``Margaret''). Gilbert feels remorse, however, upon receiving pleasant valentines from both of them, and his regret is compounded when his deceit is discovered and he is shunned by the class. An apology and two new poems from Gilbert patch things up in time for the Valentine's Day party. These hazardous waters of handing out valentines are negotiated by a cast of animals whose emotional toils will closely mirror readers' own. DeGroat pens a sympathetic look at the small hurts in life and the importance of second chances. (Picture book. 5+)