David really is not a whiner, not down deep, but if there is a weakness in Discover the Destroyer, it is David's excessive indulgence in teenaged angst: "Pleasure fades, gets old, gets thrown out with last year's fad. Fear, guilt, all that stuff stays fresh."

Part of this is motivated by his bad memories of childhood. David's memories are nothing compared to what Jalil has to go through with his mental illness, and regrets over no longer getting a thrill out of skating down a parking ramp seem way too childish for the active, even exuberant personality of David.

On the other hand, Applegate's craftsmanship is evident in the construction of Discover the Destroyer. It begins with a life-or-death problem for the teenagers, the replacement of their hearts by rubies that will go bad in six days, then passes through one thrilling event after another, to...