Hardy Boys Adventures : Into Thin Air (Vol. 4)

One minute Daisy Rodriguez was there, and the next... she was gone. Just like that. Her father, Hector Rodriguez-owner of Bay port's local amusement park, Funspot-is frantic. He feels he's to blame because two other kids recently disappeared from Funspot. Joe and Frank solved that mystery and think Daisy's vanishing must be connected in some way. But Daisy doesn't appear to have an enemy in the world. Who in Bayport wants this girl gone?