Every night water strangely disappears from the new reservoir near Skull Mountain. Frank and Joe join forces with a team of skilled engineers to solve the baffling mystery.

A chance meeting with a stranger on the road provides the Hardy brothers with a clue to a gang of local burglars.

When the Hardy Boys set out to solve the mystery of their missing chums, they discover a gang hide-out in a cave on an island along the way.

Joe and Frank investigate some pranks around Bayport, leading them to the Red Arrow, a crime grang.

Joe and Frank Hardy are attending the season's opening night at Funspot, a local amusement park that's been declining for years, but that recently got new owners and a facelift. Their friend Daisy's family has everything riding on Funspot's success: If the revamped park is a failure, her family will be broke! At first, an exhilarating new attraction is a huge hit but when one of the riders disappears into thin air, fun and games turns into spine-tingling...

College recruiters are pursuing Bayport High's football star, Terry Golden, and his clique of jocks enjoy basking in his aura of celebrity. When the hazing to become a member goes too far, the Hardy boys begin an investigation. Grades 4-7. (Hardy boys mystery stories ; 170).