After six decades of writing historical best-sellers, the octogenarian author has produced his first suspense novel. Set on Manhattan’s Upper West Side (complete with a description of Zabar’s smoked-fish counter), Redemption follows the affair of a 78-year-old contract law professor and his 47-year-old squeeze, who’s been accused of murdering her violent Olympic star ex-husband. It’s a provocative riff on the athlete-abused-wife syndrome, and Fast handles the nuances with sensitivity while probing the ins and outs of the criminal justice system. A sassy defense attorney and tight courtroom scenes underscore the post-O.J. conclusion that ”criminal trials are part evidence, part illusion, and part theater.” B