Seashore naturalist John Waters' first juvenile novel has a rolling gait and open-faced countenance that you can latch onto. . . just as orphaned Johnny Boston, alone again after his foster father leaves for California, latches on to Jumbo, the 440-pound giant who boards at the Cape Cod hotel where Johnny works. Jumbo refers to the rest of the world as ""pencils"" and has a stock of tall tales to match his dozen-egg appetite; he might be a freak or a born loser. But when he teams up with old Admiral Flame, a retired and possibly senile salvage officer, to bid on a beached freighter, Jumbo turns out to be every inch the hero Johnny imagines. The proof comes twice: first when Jumbo defeats a circus strong man in a chain wrestling contest to win the last $15,000 the investors need; then again when he directs the complicated refloating operation after the Admiral's death. Jumbo and Johnny's friends include the red-faced hotel owner everyone calls Purple, and a fortune-teller named Zaida, and this weatherbeaten group's gamble on becoming instant millionaires is a tall tale in itself. . . but the kind you need to believe can come true once in a while.