Ellen and Corey have the chance to camp overnight at the Seattle zoo; but what was planned as a special birthday present nearly proves to be the death of them when they come up against an escaped convict who thinks of the zoo as a safe hideout. When their parents' flight is delayed, Ellen (12) and Corey (8) are afraid they'll have to miss the anticipated campout, but they're able to convince the zoo administrator that their parents have just pulled into the parking lot. Anxious to leave (her daughter is giving birth), she lets them stay after-hours, with the result that the children are left unchaperoned overnight. Meanwhile, convict Tony Haymes plans to kidnap a rare baby monkey and use the ransom to flee to Mexico. As the kids are separated at various points--each trying to elude Haymes, find the other, and rescue the monkey--their experience becomes more and more frightening. When they are finally rescued, it's due in part to Ellen's ability to communicate nonverbally with the elephants. For readers who can swallow the supposition that Ellen can command a bull elephant telepathically, the book works pretty well as a suspense novel. Kehret's attention to detail is less than perfect (How does Ellen know that the trail of peanut shells she follows was left by her brother?), but she arranges the children's isolation at the zoo realistically enough, and the plot is scary. Acceptable additional fare.