Book is not Sinister Island by Camp. I read it back in the '60s. Set in Pacific during pre- or early WWII. Possibly part of series. Pilot flies near island with coves at either end and vaguely S shaped. Either shot down or crashed and discovers secret Japanese base being built. Reads a lot like early Louis L'Amour pulp. Think island was known as sinister island but may not have been in title.
Amazon has a listing for Sinister Island Squadron that may be what you are looking for. A reviewer said that it was geared for teens and Young Adult
Thanks. For some reason I only tried Google. Duh! I couldn't sleep last night and was up until 6AM. So I looked it up on Amazon. Found Sinister Island Squadron which is probably the one I'm looking for. The author who died in '51 wrote about flying in the Pacific and Amazon. However, I also found the mystery by Camp, a romance, and two more juveniles titled Sinister Island. None of the three juveniles, young adults have any sort of description.
