Penny befriends another troubled young lady, Amy Coulter. Amy's sculpture, the Black Imp, was the best entry in an art contest, but the prize went to an inferior work of art. Even worse, Amy is now accused of stealing a valuable Rembrandt painting from the museum! Penny is certain that Amy is innocent and even helps Amy evade the police. After Penny chances to see Amy accepting a payment from a man connected with the museum, Penny worries that she may have acted rashly in helping Amy maintain her freedom. Penny unearths several important clues, the most shocking one in the home of a wealthy citizen. Soon, Penny learns the identity of the real thief and makes an astounding discovery about Amy's Black Imp.