It’s the 17th book in the series, which began in 1933 with The Case of the Velvet Claws. In the previous books, the policeman that Mason most often ran up against while defending his client was Sergeant Holcombe of the LAPD’s Homicide bureau.
Holcombe wasn’t terribly bright. He hated Mason with a passion and always worked on the assumption that Mason was committing any number of crimes—from perjury to hiding evidence—to protect his clients. But Mason would always run mental rings around the poor guy, outsmarting him at every turn.
Holcombe wasn’t without his good points--in one book, after Mason has identified the real killer, Holcombe brings the guilty man down even after taking a couple of bullets. But his brutishness and slow-thinking didn’t make him much of an adversary.
So, in Silent Partner, Holcombe is transferred (mostly because Mason keeps making him look foolish) and Lt. Tragg is assigned to Homicide.
Tragg’s a good cop. Mason learns this early in the novel when the two have to team up to track down a woman who has apparently been poisoned. It’s Tragg’s skill as a detective that brings them success.
Mason has to pull a few fast ones (including generating circumstantial “evidence” that indicates his client has also been murdered) to identify the real killer. This isn’t easy. Tricks that would have had Holcombe baffled don’t fool Tragg for a moment. Before the novel is reaches its climax, Mason’s shenanigans have nearly gotten both him and his secretary Della Street tossed in the slammer. But Mason manages to stay barely one step ahead of Tragg and the lieutenant is at his side when he confronts the real killer with enough evidence to elicit a confession.
As is typical with Erle Stanley Gardner’s work, the plot is a good one, moving along quickly and giving us a really cool twist at the end. But it’s the dynamic between Tragg and Mason that really makes this novel stand out from the others in the series. Mason now knows he has a wily adversary. He realizes that in the future, when he stretches (but never quite breaks) the law to help his clients, he’s really going to have to watch his back.