Friendship doesn't come from secrets...unless blackmail is involved.It doesn't seem like Owen, Gemma, Todd, and Ally have anything in common until a mysterious puppet master emails each seventh grader claiming to know their secret. Each of their respective secrets will be revealed unless the four puzzled (and scared) students do exactly what the blackmailer commands. Over the course of the following school day, the foursome must work together to complete what initially appears to be a series of meaningless tasks that slowly become more and more sinister. Suspects abound as the four try to determine what connects them, the tasks they're forced to complete, and how both relate to a potential fifth victim. The twists and turns offer thrills as the narrative shifts among each of the four victims as well as a transcript of their conversations as they try to piece together clues. Readers may feel cheated, though, when the blackmailer is finally revealed, as the clues and the denouement aren't fully linked. Additionally, resolution leaves a lot to the imagination: Did the blackmailer work alone? What ultimately happens to the blackmailer? What were the ramifications of the day? It's an entertaining story, but the finale is less than satisfying. Main characters default to White; Ally was adopted from Kazakhstan, and names signal diversity in the supporting cast.Fun but inconsistent in execution. (Mystery. 9-12)