Jimmy Novak's daredevil prank coincides with a towboat accident on the Mississippi that almost claims his father's life--in a suspense-filled story that should make readers ponder the value of the macho image. "Thonker" was the affectionate nickname that the surgeon who treated Jimmy's knee injury gave his young patients; Jimmy and two of his friends adopt it for their exclusive club, vying with one another as stoical survivors of whatever major or minor pain they encounter--or inflict. When Jimmy's cousin David comes to stay while his widowed mother has heart surgery, they callously exclude him--he's not only younger, but unforgivably wimpy. The three older boys engage in a stunt involving a railroad drawbridge, and are sobered by the danger they finally comprehend after escaping intact; coming home, Jimmy learns that his father is missing--and during the harrowing night that follows, he comes to understand the courage that David has shown during the uncertainty about his mother. Like Bauer's On My Honor, Thonkers makes compellingly real the tragedy that can result from youthful recklessness. Naylor's thoughtless boys are well-drawn, normal kids from warmly loving blue-collar families; Jimmy's Mom--whether wisely waiting for him to make his own peace with David or cleaning cupboards at one a.m. while she waits for news of her husband--is only one of the sharply sketched adult characters. It may take a booktalk to get fifth graders past the title here, but they'll love the book.