Stone and Anvil — Peter David

A crewman has been murdered aboard the U.S.S. Trident, and all evidence points to Ensign Janos of the Excalibur. Captain Mackenzie Calhoun is reluctant to accept that Janos, a powerful non-humanoid whom the captain has known and trusted for years, could be a killer, and immediately launches an investigation into the crime. But this troubling murder mystery soon escalates into a full-fledged diplomatic crisis that threatens to pit Calhoun and Captain Elizabeth Shelby against the entire United Federation of Planets -- and the Starship Enterprise™.

Meanwhile, the turmoil involving Ensign Janos forces Calhoun to recall his own tempestuous past, his rocky relationship with a young Elizabeth Shelby -- and a long-ago exploit that may have everything to do with the deadly emergency that now confronts them all!