Em & Jules Case 2: The Whisper

From the Publisher:

Em Smith finally has what she wants. But when the power goes out at the dance, she and Jules realize someone has stolen the homecoming crown. With another mystery at hand, Em and Jules enlist Em's crush, Kyle, for help. They also find help from a very unlikely source in order to track down the crown and prove themselves to the high schoolers, who are performing their own investigation. Through it all, Em struggles with feeling like a third-wheel on the new mystery team, but in the end, it’s up to her to find the culprit.