Have I got a treat for those who prefer to celebrate their holidays in hard-boiled, rather than Hallmark, style. It’s a heavyweight of a collection called “The Big Book of The Continental Op” that gathers together the 28 short stories, two novels and one unfinished tale starring Dashiell Hammett’s first series detective, known only as “The Continental Op.” “The Big Book of Continental Op,” by Dashiell Hammett (Vintage Crime/Black Lizard) For those readers who haven’t yet run into him, the Op is middle-aged, overweight and nameless. His moniker derives from his job: He’s an “operative” or detective, who works for the Continental Detective Agency. He’s easy to underestimate, but that would be a mistake. In the Op, Hammett revolutionized the traditional figure of the detective, strong-arming him out of his Sherlockian smoking jacket and into an American-made trench coat, shoving him out of his armchair and down those dark alleys where the most realistic crimes are waiting to be solved. Hammett paid tribute to his first great literary creation by referring to him as “a little man going forward day after day through mud and blood and death and deceit.” Hammett wrote The Continental Op stories in the earliest years of his career, and to read them in sequence is to witness how Hammett slowly transformed the formulaic “gals, guts, and guns” action tales, the staple of pulp magazines like the Black Mask, into the stuff of literature. Even the early Op stories here give readers the chance to walk around the mythic San Francisco that Hammett created — a place of fog and furnished apartments, sinister Nob Hill mansions and Chinatown gambling dens. [The 10 best thrillers and mysteries of 2017] This collection is edited by the distinguished Hammett scholar Richard Layman and Julie M. Rivett, who is Hammett’s granddaughter. In a couple of short-but-substantive opening essays, Layman sketches out the sources of the Continental Op stories in Hammett’s own five-year career working for the Pinkerton National Detective Agency. That career was interrupted by his Army service in World War I, where he contracted tuberculosis. In 1922, Hammett (by then on disability and a married