Baby Reindeer is not what you expect.

Initially, you think you’re watching a television series about a stalker. Then it’s a show about sexual grooming. By the time you’re done binging the seven-part anthology series, you’re not sure what you just saw. But you’ll never forget it.

The year’s best show so far flew virtually under the radar when Netflix introduced it earlier this month. And a full two weeks after its release, Reindeer managed only nine critic reviews.

But it’s telling that not a single review on RottenTomatoes is negative. While the show may not be everyone’s cup of tea, its writing, craftsmanship and storyline is so riveting there’s no taking your eyes off Richard Gadd, the creator and star of Reindeer.

The film is based on a true story in which Gadd received more than 41,000 texts and 350 emails from a stalker. While Gadd changed the names and some circumstances to protect real people, he nails real emotion on the head.

Gadd plays Donny, a hopeful comedian who works at a British pub and comes across Martha (Jessica Gunning), a woman who claims to be a successful lawyer, but who can’t afford a Diet Coke. Everything about Martha screams loser — except Martha, who appears brimming with confidence. It’s a lovely glimpse at what we consider attractive, and who gets to decide.

Not long after Donny offers a kindness, things go south in a hurry. Where Gadd’s phone blew up in real life, in Reindeer Donny’s email is inundated.

And it’s here, in the show’s portrayal of mental disorder, that it sets itself apart from every other show on TV. The series bristles with misspellings and off-acronyms as Gadd utilizes the manic missives to wondrous effect. When I was a police reporter in Detroit and D.C., we had an offhand rule: If the letter to the editor is written past the margins, the writer is loony.

Reindeer takes place on-screen, but its narrative brilliantly blows by any margins. You can feel the series’ tensile strength straining with each note sent.

As Donny flees the unwanted advances, he finds himself making poor (though understandable) decisions that simply compound the problems in his life.

Halfway through the show, you won’t know who poses the real threat to Donny — including Donny. You pull for characters you’d never expect, turn on those you once thought true.

Kind of like life. Kind of like love.

What a find! It’s hard to lament the death of the big screen when the small one keeps cranking out gems like this.

Some critics will eventually pan Baby Reindeer. But you can bet they never took their eyes off it.