Dear Dan,

Okay. I get it, now. It’s all starting to make sense.

For a long time, though, I didn’t understand. You left one of the most popular television series in the English speaking world at the peak of its popularity to pursue other roles. But there was no blockbuster superhero flick on the horizon, no colorful supporting part in a Paul Thomas Anderson ensemble. Instead, your first post-Downton gig was the lead in a low-budget thriller that pays homage to low-budget thrillers. Which, forgive me, didn’t seem like the wisest career decision. Even Hugh Grant knew well enough to milk his stuttering English charm for a few more flicks before trying his hand as the star of a Hollywood suspense film.

But it turns out that The Guest is more than just a movie-geek trifle. And if you were looking to exorcise the elegant, befuddled specter of your Downton Abbey alter ego Matthew Crawley, there was no better role than this. As the mysterious stranger who shows up to pay his respects to the family of a fallen army comrade, you have established your place in the company of cinema’s all-time great tough guys. You, sir, are no Hugh Grant.

The Guest might as well have been subtitled A Series of Gratifying Revenge Fantasies. Throughout the film, schoolyard bullies are brutally punished, lecherous ex-boyfriends are publicly shamed, and professional rivals disappear under suspicious circumstances. But simply bringing to life juvenile daydreams of comeuppance doesn’t a great film make. And The Guest is a great film (one of 2014’s best, according to at least two highly-respected film critics).

Much of this greatness is in the film’s clever confounding of expectations. Director Adam Wingard achieves this by rooting the style and narrative in a familiar place: the world of cheap, violent videocassette thrillers (think early John Carpenter, or The Stepfather). But as the film progresses, he begins to break the rules. Our assumptions are, every few minutes, recalibrated. Apprehension turns to attraction. Attraction turns to suspicion, then repulsion. And in the very last moments of the film, impossibly, that repulsion becomes admiration. It’s classic sleight-of-hand. It looks like he’s playing a familiar magic trick, but while you’re watching closely for wires and mirrors, you realize he’s pulling off something much grander.

That’s a difficult feat for any filmmaker. And an even more difficult feat for the actor who must embody all those subtle (and not-so-subtle) shifts. But both of you pull it off. Even the carefully-curated soundtrack is proof of Wingard’s movie-nerd bonafides: it gets the tone exactly right, all drum machine beats and ominous synth swells. The typeface of the titlecard, too.

But I’m making it sound like a The Guest is some kind of esoteric metatextual experiment. It’s really just an excellent capital-M movie, built from a series of excellent movie moments. All of which focus on your character. Ultimately it’s your performance that elevates The Guestpast the conventions of the genre. The uncompromising stare, those blazing eyes, that swagger, that smirk—in most films, all of that coolness would simply be in service to the star’s ego. But your seduction of the audience, here, is to a greater purpose. And somehow you pulled it off while wearing a hoodie and a crisp golf shirt.