THE POWER OF UN

Etchemendy (Crystal City, not reviewed) mixes quick action and long thoughts in this tale of a lad who discovers that changing the past is a tricky business. When a gimpy old man, smelling of ozone, pops up from nowhere and hands him a palm-sized time machine, Gib Finney is understandably dazzled by the possibilities. But his excitement changes to anguish when he loops back in time to prevent first his little sister, then her sitter, from being run down by a truck, and learns that there’s a momentum to events that is hard to divert. Gib’s increasing desperation, as he tries to figure out how to head off what he knows is about to happen, injects suspense into the story, and his misadventures with the “unner” prompt insights into how minor incidents or casual choices often have far-reaching, unpredictable consequences. In the end, he does manage to keep anyone else from being hurt, at the cost of having his own leg crushed (readers will have twigged to the mysterious old man’s identity long before this) and the “unner” suffers the same fate. This hangs together better than William Sleator’s similarly premised Rewind (1999), but readers who assume from the cover illustration that it's a comedy are in for a shock. (Fiction. 10-13)