There’s a Big Dose of Humor in ‘Slight Case of Murder’

“A Slight Case of Murder” is homicide most whimsical, a TNT film of effortless fun that piles up many more laughs than bodies.

Credit mostly Steven Schachter and William H. Macy. The underpinning of this black comedy is their sweetheart teleplay, based on a novella by Donald E. Westlake. In addition, Schachter directs with humor, and that under-sung national treasure, Macy, again showcases his mastery of squinty antiheroes who hide amorality behind straight faces that project meekness and befuddlement (think Jerry Lundegaard in “Fargo”).

The cad Macy plays here is Terry Thorpe, a minor movie critic who reviews for local TV. “Uh, cable TV,” he adds self-consciously.

Thorpe has himself a bit of a crisis, you see. It begins when he accidentally kills his secret lover, a CBS executive, during a quarrel in her apartment. Instead of calling the police and telling all--end of story--he decides to cover his tracks so that his girlfriend, Kit (Macy’s wife and “Sports Night” star Felicity Huffman), won’t discover he’s been two-timing her. The result? Disaster.

We can look the other way and forgive Schachter and Macy for wedging in this plot point. They need the illogical ruse by Thorpe to drive the rest of their plot, which finds a corrupt and menacing private detective named Edgarson (James Cromwell) immediately learning what happened. He demands $35,000 to keep quiet, forcing Thorpe into extreme action that’s in the best tradition of farce.

All the while, Thorpe narrates his own story, and unburdens his soul to the camera that he makes his confidant. “This is hard. I have newfound respect for actors,” he says at one point after lying to police.

One of them, Det. Fred Stapelli (Adam Arkin), is a cop with a screenplay for Thorpe to read. And the critic’s subsequent chumminess with Stapelli and his chirpy wife (Julia Campbell) creates unexpected complications.

No one is better than Macy at hemorrhaging insincerity with comic intent or at making you somehow pull for his character to come through clean despite the guy’s nefarious activities.

And especially clever is Thorpe’s attempt to extricate himself by seeing his dilemma through a critic’s lens. “Don’t worry,” he tells the camera while slipping a mysterious powder into a woman’s drink. “I know this looks like a scene out of ‘Notorious.’ I’m not Claude Rains. I’m more like John Cassavetes in ‘Rosemary’s Baby.’ ”

There’s no supernatural horror in “A Slight Case of Murder,” though. Only great amusement.

* “A Slight Case of Murder” airs Sunday at 8 p.m. on TNT. The network has rated it TV-14-LV (may be unsuitable for children younger than 14 with special advisories for coarse language and violence).