Lazar, Ralph. Total mayhem #9

Cover title

"One of the most exciting events of the year is taking place at Swedhump Elementary: Marble Day. When the grand-prize, the World's Most Famous Marble, gets stolen, and then recovered, it seems as if all is well. But then things begin to rapidly unravel. Dash, Greta, Rob and Ellen have a mystery to solve, and fast! This action-packed adventure takes our heroes straight into the face of danger. Can they outwit and out-maneuver a cunning gang of enemies?"-Back cover