The Bones in the Cliff — James Stevenson

And day now the big man with the cigar might be arriving on the ferryboat--the man that Pete's father is terrified to see.

So three times a day, when the ferry is due at the island, Pete jumps on his bike and races to see if the big man will get off the boat. In Pete's pocket is a quarter, so he can rush to the telephone and warn his father.

It is not until almost the end of summer that Pete finds out why his father is so afraid. But in the meantime he has met eleven-year-old Rootie, an old-timer on Cutlass Island, who shows him the island newcomers never see--and who helps him face the danger when it finally arrives.