I began P.G. Sturges’ debut thriller, “Shortcut Man,” hoping it would make me laugh out loud, grab my interest with a wildly inventive plot and, ultimately, touch me. Such are the responses that Sturges’ father, screenwriter-director Preston Sturges, elicited in a series of brilliant film comedies shot in the 1940s — “The Miracle of Morgan’s Creek,” “Sullivan’s Travels,” “The Lady Eve” and others.

This was a big order, and maybe not a fair one as it holds son up to legendary father. But I couldn’t resist. And P.G. Sturges shows again and again that he’s one apple that has fallen smack under the tree.

I started laughing by Page 5. I found a scene during a Catholic Mass poignant, and although Sturges stays within Raymond Chandler’s noir template, his PI Dick Henry and a caravan of sociopaths kept surprising me as they careened from Laurel Canyon to Big Sur, where a stunning finish plays out.

Henry, who narrates most of the action, begins by explaining that he’s the shortcut man people turn to when the wheel of law turns too slowly. Henry’s sense of vigilante justice percolated over time, boiling over when, as a Los Angeles cop, he responded wildly to a wrenching incident involving a child. His superiors suggested he resign. So now when he smells a stinker, Henry pummels the stinker’s face.

This happens in a prologue when Tisdale, a 300-pound, 6-foot man with “rat eyes,” begs off paying rent because his mother is ill.

Henry weeps buckets: “According to my preliminary investigation, his mother died five times. Three times of cancer, twice of tuberculosis, one of intestinal blockage. Wait a second. That made six.”

Impressed by Henry’s direct and efficient modus operandi, Artie Benjamin, a porn producer, summons the private eye to his office. Benjamin suspects his wife, Judy, of an affair and wants Henry to trail her.

At a cocaine- fueled, orgiastic party, Henry spots Judy. He is positive she’s having an affair — because it’s with him.

The PI knows she’s trouble. At one point, Judy muses, “Killing someone who deserves to die isn’t murder.” But he’s besotted. In a line worthy of Bogart or Mitchum, Henry admits, “Part of me knew I wouldn’t have her long. That was what made the living tragedy so sweet.”

When Henry comfirms Judy’s infidelity to Benjamin, the porn king asks for a name. Henry invents one. Benjamin pushes $50,000 at Henry and says he wants him to kill the guy. Henry finagles to get an obituary for the imaginary adulterer published. Then Benjamin wants to see the body.

Meanwhile, Judy is also carrying on with Benjamin’s assistant, Arnuldo, a killer who began his career in Manila at age 12 by butchering the man who sold his mother the heroin that killed her. Judy enlists him to take out Benjamin while she remains in his will.

It’s not surprising that after all he has seen and done, Henry is a cynic with a trashy mouth. (Be forewarned: His sendups of women, gays and a black man throw political correctness to the Santa Ana winds.)

But hard-bitten as he is, Henry also shows compassion. In an affecting subplot, he goes after a grifter who’s bilking a 78-year-old man out of thousands of dollars. As the man’s daughter sobs, Henry reflects: “Again I was reminded that all of us had suffered terrible blows, that we were the walking wounded. Fractured, crushed, punctured, abraded, lacerated.”

Since Henry remains virile and aggressive in middle age, he’ll likely return in further installments to sleep with more treacherous dames and break the thumbs of creeps who menace the fair and innocent.

It’s a shame Sturges’ father isn’t around to film these capers. Oh, what he could have done with Alan Ladd and Veronica Lake as Henry and Judy.