Amateur avengers with special talents team up to bring down traffickers in human body parts--in a chilling medical thriller from Chiu (Port Arthur Chicken, 1979, etc.). When a teenager from the Mexican village where he's been sent by MÃ¢decins Sans FrontiÂ²res disappears on his way to the US, Dr. Nguyen-Anh Dupree asks hacker friends in Los Angeles for help in determining the boy's fate. The coed computer wizards Ignacio Tejada (a grad student whose brother heads one of the city's toughest gangs) and Phillipa (Leepi) Walker (employed in the motion-picture industry) accept the challenge. But the cyberspace trail dead-ends at Caduceus 21 (a closely held HMO) and MedEx (another extremely private transnational enterprise that specializes in flying transplant organs from donors to recipients). Meanwhile, investment banker Maggie Sepulveda is vetting C 21, which needs to raise expansion capital. The supposedly routine examination takes an unexpected turn when one of her subordinates unearths evidence that the health-care concern may be cooking its books. After the hapless auditor is murdered and Dupree (now on home leave) apprises her of his own suspicions, the fledgling financier quickly joins forces with an Amerasian physician, Nacio, and Leepi. The foursome soon smokes out the real villain of the piece, a nonagenarian billionaire known as Century Chisolm, who holds controlling interests in both C 21 and MedEx. With his anonymity in jeopardy, the rogue industrialist desperately tries to keep the lid on. Chisolm's personal intervention proves unavailing, however, as the quartet succeed in rescuing Maggie's mom (who's been abducted), hacking into ultrasecret memory banks, learning the details of a custom-killing operation that provides contraband body parts on demand, and arranging for incriminating corporate data to be transferred to computer files maintained by the Justice Department. At the close, moreover, they impose an appallingly appropriate punishment on Chisolm for institutionalizing a black market in replacement organs. An engrossing and literate shocker.