Conflicting motives almost wreck a third grader's firm friendship with his brother in this easy-reading, easygoing family story. A month after their sister's hyperaggressive cat Caliban disappears, Jamie and Gordon feel safe in buying the mice they've wanted for so long--but Jamie, who loves Scrub and Digger as pets, is horrified to learn that Gordon plans to sell their offspring for snake food. To make matters worse, shortly after the miracle of birth brings Ralph, Whiskers, Nosy, Smart--etc., etc.--into the world, Caliban returns, much worse for wear. Are the mice doubly doomed? No. Caliban seems to be a changed cat, and Jamie cleverly persuades penny-pinching Gordon to change his mind by adding up the cost of keeping an explosively expanding""inventory."" Nonstereotypical characters and plausible problem-solving mark this light tale; Smith's b&w line drawings, as usual, capture each significant moment with deftly depicted facial expressions and body language.