Katie takes her sisters to a concert for their birthday, and while there, she is approached by the singer herself to solve a mystery. Sheena Shield is being stalked by a note-writing fan, but when her lucky charm, an emerald pendant with a double "S" on it, goes missing, Katie now has two mysteries to solve for the pop star. Can she tie them together, or are there two villains? Find out in the 19th Katie Carter Mystery Story - Katie and the Case of the Double "S" Pendant