Caroline Dhavernas in Lifetime’s "Mary Kills People." (Christos Kalohoridis/Lifetime)
Senior Editor for Style

Lifetime’s “Mary Kills People,” a six-episode series that is probably not destined to be new Supreme Court justice Neil M. Gorsuch’s favorite binge, is a provocatively compelling and occasionally nail-biting tale of an emergency-room doctor, Mary Harris (“Hannibal’s” Caroline Dhavernas), who is secretly running an assisted-suicide operation for patients who are terminally ill.

At $10,000 a pop, Mary and her charming assistant, Des (Richard Short), come to their clients’ homes (or meet them in a secluded location, such as a beach at sunset), have them testify their final wishes on video and then serve them a nighty-night cocktail that is mostly pentobarbital, which Des, a recovering addict who lost his plastic-surgeon license, obtains from Grady (Greg Bryk), a temperamental drug dealer.

Before viewers can get accustomed to Mary’s routine as Dr. Death and all the sneaking-around it involves, she encounters two setbacks: One of her teenage daughter’s good-for-nothing friends discovers the pentobarbital stash and helps herself, winding up in the ER. Worse, one of Mary’s terminally ill clients, Joel (Jay Ryan), is an undercover cop who has been on Mary’s trail for weeks. She learns this only after they’ve had sex.

Messy, complicated, and yes, just north of plausible. Somewhere along the way, “Mary Kills People,” created by Tara Armstrong, was billed as a dark comedy, but that’s the wrong shelf — it’s a serious and stylishly watchable drama, thanks mostly to Dhavernas’s capable performance of a morally ambiguous person with too many dangerous irons in the fire, and Ryan’s portrayal of a hurt-and-handsome lawman struggling to do his job, even though he’s in love with his suspect.

The doctor digs herself deeper into trouble — perhaps past the point where a viewer will continue to root for her and her merciful cause. “Mary Kills People” remains firmly in favor of assisted suicide, suggesting that Mary’s good intentions are thwarted by the insensitivities of law, particularly the fact that a local judge blames her for the death of his son, hence the undercover investigation.

And then there’s the slight nagging feeling one gets when watching (or reviewing) a show such as this: If it’s on, why haven’t I heard more about it? What city are they in? Why don’t I recognize most of these actors? Why is this pretty good (with the potential to be as good as TNT’s similarly taut “Good Behavior”) but not really that great?

The answer finally dawns: It’s Canadian.

Canadian shows! Those hosers — they’ll sneak one past you any chance they get, but I have to give “Mary Kills People” credit, because I got all the way to the fifth episode before I smelled even a trace of poutine. And anyhow, no matter who produced it or where it was filmed, “Mary Kills People” had me hooked until the end. With more mediocre junk available than we can possibly watch nowadays, that’s one of the highest compliments around.

Mary Kills People (one hour) premieres Sunday at 10 p.m. on Lifetime.