While serving school detention in the soup kitchen at St. Mary's church, Sammy finds herself the prime suspect in the theft of Father Mayhew's ivory cross. But there have been other robberies at the church recently, and as Sammy attempts to discover the real thief, all the suspects appear to be religious figures who are above suspicion. That is, until Sammy cuts through disguises to uncover an enormous heist! Of course, solving the mystery would be a lot easier if Sammy wasn't also trying to fend off dirty tricks from her arch-enemy Heather, and helping her softball team win the playoffs. Then there's the gospel singing nuns known as the Sisters of Mercy... the excitement doesn't end in one of the funniest and feistiest adventures in the life of the inimitable Sammy Keyes!