Jonathan Stroud's "The Amulet of Samarkand" featured wonderful characterization and tight, suspensful plotting. It's all the more puzzling, then, that his contemporaneous effort, "The Last Siege," is weak on both counts. "The Last Siege," as best I can tell, represents Stroud's attempt to look at the potentially destructive effect of an overactive imagination on a child. An interesting idea in theory, perhaps, but a snore as written. The plot, such as it is, is pointless, and the characters are both thinly-drawn and utterly unsympathetic. Stroud is clearly a gifted writer -- but this is not his best work.