This is a sequel to last year's It Started with Old Man Bean, in which 11-year-old Ted and his buddy Joe camp out in the early Forties Wisconsin wilderness and are scared off by a possibly human ""owl hoot"" in a cave. Beyond Two Rivers (the writing no subtler than the title) has a bit more in the way of conventional tension, as the two boys return to their campsite with plans to hunt out the ""Jap"" spy they imagine responsible for the sound--and for a small man's sneaker print they spot near the river. They do meet a man in the wilderness, a wise and patient hermit who catches rainbow trout with a bow and arrow, teaches them both about the ways of nature and their own progress toward maturity, and teaches each boy separately what he wants to learn--Joe about trapping animals, Ted about drawing plants. The man speaks perfect English and says his parents were born in America, but his name is Mr. Matsumoto, he refers to the raisins of California, and Ted knows immediately that his is the ""Jap"" they came for. Mr. Matsu, though, is so obviously their friend and so obviously to be trusted that it isn't hard to convince Joe he's not a spy and not to be reported. As in. . .Old Man Bean, Kherdian conveys a feeling for the wilderness and the time of his youth, but overdoes the boys' callow savoring of their experience. (Their airy references to their ""java and Old Golds"" would be enough without Ted's repeated explicitness about the ""manly feeling"" of camping out on their own.) They also ooh and ah excessively, at first over a sports' reporter's trout-fishing skills (a mere prelude to Mr. Matsu's); and Matsu's freeze-dried guru wisdom is laid on especially thick.