An absorbing account of an ""insanity"" defense based on biochemical rather than psychogenic evidence. One night in 1974 a young Massachusetts man--the pseudonymous ""Charles Decker""--picked up two teenage girls hitchhiking, rode around aimlessly with them for a while, drank a little beer, and then suddenly smashed in their skulls with a stonemason's hammer. (They survived, but barely.) Later that evening young Charles was aghast and called his father: ""Daddy, I don't know. I went ape."" Under the circumstances, it didn't hurt that daddy was an endocrinologist and a long-time friend of Dr. Mark Altschule, a specialist in the ""biochemistry of mental disease"" (as Charles' lawyer phrased it) and former chief medical officer of ritzy McLean Hospital near Boston. Altschule had treated Charles previously (there was some history of violence that defense counsel managed to keep out at trial) and, from the wild, out-of-nowhere nature of the attack, suspected a problem in the limbic system--the primitive inner fifth of the brain, dominated in man by the highly developed cortical system. (A crocodile's brain, by contrast, is mostly limbic system.) Tests administered by Altschule indicated that Charles had Korsakoff's syndrome (often, but not always, associated with alcoholism), suggesting a limbic lesion; and chemical analysis showed a definite alcohol metabolism abnormality. When Charles drank, his lawyer argued, an unknown, toxic substance was released into his bloodstream, damaging his brain and sometimes causing violence. Deep water indeed for a local judge, who nonetheless coped admirably with the novel defense theory during a lightning-fast (three-day) nonjury trial. The Solomonic verdict: guilty of attempted murder, suspended sentence, fight probation restrictions (including, of course, no drinking). For Mayer and Wheeler, the outcome shows how a court can ""improvise a rule of diminished capacity"" as a ""sensible response to artificial insanity rules."" Perhaps. Or was the court simply conned? That excluded history of alcohol-related outbursts was crucial: the defense case hinged on arguing Charles' lack of responsibility for the ""unexpected consequences"" of drinking; but if it had happened before, Charles should have known the consequences. Was justice done? Or does the Decker case teach only that, with an endocrinologist father and $30,000 in legal fees, you too can get away with attempted murder? Mayer and Wheeler seem persuaded of the former view. A well-told story (with short excursions into the history of the insanity defense, biopsychiatry, and psychosurgery)--that may, just now, attract interest outside the criminal-justice and mental-health communities.