A second period outing for medium-boiled shamus Harry MacNeil--but without the textured jazz-world atmosphere that gave Rubout at the Onyx (1981) some distinction. This time, circa 1939, it's murder at Radio City, where Derek Worthington--the star/producer of radio's popular Detective Fitzroy's Casebook--is found shot to death in the studio. Top suspect? Announcer David Reed, whose ambitions were crushed by nasty Worthington. The key clue? The gunshot was heard over an open mike--giving the murder's, exact moment. . . when everyone but Reed had an alibi. Still, urged on by Reed's girlfriend, MacNeil goes sleuthing--soon learning that foul, womanizing Worthington was hated by many, especially now that he was planning to leave the show for Hollywood. Eventually, after a Radio City tour-guide turns up dead, MacNeil realizes (long after most readers will) that the gunshot-clue might be a fake. And the windup, heavily indebted to Agatha Christie, is an implausible trick-twister. Pleasant, passable nostalgia-with-mystery fare--but neither vivid in the 1939 setting (despite a young Ed Sullivan cameo) nor amusing in the backstage goings-on (especially in contrast to the show-biz mysteries of Simon Brett).