The Phantom of the Circus (Ozark Adventures #3)
Gilbert Morris
Fourteen-year-old Barney and his brothers try to find the person responsible for sabotaging the circus where the boys are working for the summer.

by Elspeth Campbell Murphy (1995)
The three cousins are stuck babysitting their bratty third-cousin Patience and when she disappears while they are visiting an old mansion, they must investigate.
Gilbert Morris
Fourteen-year-old Barney and his brothers try to find the person responsible for sabotaging the circus where the boys are working for the summer.
Mary Duplex
While working on a community clean-up project, four oddly matched fifth graders are led by God to investigate a mystery involving missing pets and a homeless woman.
Jerry B. Jenkins
Dallas O'Neill and his friends try to find out what is behind the strange behavior of the older sister of one of the members of the Baker Street Sports Club.
Sigmund Brouwer
Ricky and friends attempt to solve a century-old mystery of military theft in Charleston, South Carolina, while they also prepare to face an approaching hurricane.