Book #3 in the Monster Kid Detective Squad series! Rico Gillman, a young sea monster in Frightsville, is having a fantastic time at the Saturday Swim Meet. But suddenly dark clouds gather and a shocking thing happens: a woman everyone can see right through appears on the high dive and seems to be calling for help. Rico finds out from his friend Theresa that the woman on the diving board is Theresa's great-great-grandmother, who disappeared...