Franklin W. Dixon 
Fish-Faced Mask of Mystery 

Its Career Week at Bayport Elementary, and Frank and Joes school assembly turns up some interesting guests. One students uncle is an animal trainer who brings a chimpanzee. Another girls father is an anthropologist who brings in a mask decorated with feathers and shells from a Pacific island. But when the assembly is interrupted by a fire drill, the mask is stolenand the Hardys spring into action.