Some spoilers follow.

“Baby Reindeer,” Netflix’s absorbing, claustrophobic seven-episode thriller, has been an unexpected global hit — a success made even more surprising given its intense themes. It is far and away the most-watched show on Netflix, according to the streamer’s publicly released numbers, dwarfing every other show on the platform.

The mini-series follows the character of Donny Dunn, a bartender and floundering comedian trying to navigate the fog of trauma and cobble together a sense of self while being mercilessly stalked and tormented by a woman named Martha, with whom he maintains a codependent connection, despite the harassment. The title refers to one of Martha’s many nicknames for Donny.

Here’s what’s real about “Baby Reindeer,” and what viewers seem most curious about.

Yes, That Is the Real Guy

“Baby Reindeer” is the work of Richard Gadd, 34, who plays Donny, a slightly fictionalized version of himself. And if you were wondering how a regular guy could be such a confident, complex actor, it’s because he is a seasoned, award-winning performer who parlayed his autobiographical one-man show, titled “Baby Reindeer,” into the series, for which he wrote every episode.

But once upon a time, he was the self-loathing performer we see depicted. “Baby Reindeer” takes meta storytelling to new levels.

Yes, It Is Based on His Real Experiences

Early in the first episode, a message across the screen reads, “This is a true story.” And it is.

“It’s all emotionally 100 percent true,” Gadd, who was the real-life victim of the stalking, said in a recent interview with Variety. “It’s all borrowed from instances that happened to me and real people that I met.” True with the caveat that “for both legal and artistic reasons,” as he put it, details had to be changed. “You can’t just copy somebody else’s life and name and put it onto television,” he said. “We were very aware that some characters in it are vulnerable people,” he added, “so you don’t want to make their lives more difficult.”

The series is largely punctuated by language from real messages sent by his stalker (played by Jessica Gunning), which we see typed out onscreen. In his one-man show, a 70-minute monologue that premiered at Edinburgh Festival Fringe and would go on to win an Olivier Award (Britain’s equivalent of the Tonys), Gadd played her voice mail messages to the audience, and projections of her emails scrolled across the venue’s ceiling.

According to Gadd, she sent him over 41,000 emails, tweeted at him hundreds of times and left him 350 hours of voice mail over the course of a few years.

For the series, certain timelines were moved around “to make them pay off a little better,” he said. Nonetheless, “it’s a very true story.”

Gadd Has Asked Viewers Not to Dig …

While the saga, at first glance, is one of stalking and obsession, it is equally about the life-shattering effects of sexual assault. In the fourth episode, Gadd’s character is repeatedly drugged, assaulted and raped by a powerful television writer named Darrien O’Connor (played by Tom Goodman-Hill) who’d made false promises to help catapult the comedian’s career. (The sexual assaults were explored in Gadd’s earlier solo show “Monkey See Monkey Do.”)

“Abuse leaves an imprint,” Gadd recently told GQ magazine. “Especially abuse like this where it’s repeated with promises.”

The depiction of the abuse is graphic and disturbing, and knowing that the characters were based on real people prompted great interest in the identities behind them. But Gadd was quick to urge viewers to stop investigating. “Please don’t speculate on who any of the real-life people could be,” he wrote on Instagram. “That’s not the point of our show.”

… Yet Viewers Keep Digging

As more and more people binge the show, social media platforms have become amateur detective rings, with viewers trying to suss out the identities of the characters. The British writer and director Sean Foley was the subject of online threats when some thought that he was the real-life Darrien character.

“Police have been informed and are investigating all defamatory abusive and threatening posts against me,” Foley said in a post on X (formerly Twitter) in late April.

On Instagram, Gadd defended Foley specifically, writing, “People I love, have worked with, and admire (including Sean Foley) are unfairly getting caught up in speculation.”

In the first episode, Gadd’s character searches Martha’s name online and uncovers a trove of articles about her past stalking — “Serial Stalker Sentenced to Four and Half Years,” reads one headline — which led some online sleuths to try to find the actual versions of those same articles.

The show has become such a phenomenon that The Daily Mail published an interview with a woman purporting to be the “real” Martha, lodging her complaints about the show, though her name was not disclosed.

When GQ asked Gadd what the stalker might make of the show, he said, “I honestly couldn’t speak as to whether she would watch it,” calling her “an idiosyncratic person.”

“We’ve gone to such great lengths to disguise her to the point that I don’t think she would recognize herself,” he said. “What’s been borrowed is an emotional truth, not a fact-by-fact profile of someone.”