Randall Peffer, who teaches literature and writing at Phillips Academy/Andover, also is a prolific writer. Among other things, he’s written tons of travel and sailing articles for National Geographic, Smithsonian, Reader’s Digest, and other magazines, and his work has appeared in most of the nation’s big newspapers. He’s also the author of the Cape Island series of mystery/thrillers starring Michael Decastro, a former public defender from Bedford, Mass., who has deep-sea fishing in his blood.