In the new horror film “The Twin,” Logan Donovan, who grew up in San Anselmo, has found his most challenging and satisfying acting partner yet: himself.

Directed by J.C. Doler in his feature film debut and co-produced by Donovan, who graduated from then-Drake High School in 2003, “The Twin” focuses on a man named Nicholas who experiences horrifying visions of his doppelgänger while dealing with the death of his son and the fraying of his marriage. Originally titled “The Speck” after a folkloric Irish spirit whose presence foretells impending death, “The Twin” won best screenplay at 2021’s Screamfest and made it to the Black List, an annual survey of the best unproduced scripts in Hollywood, that same year. After being picked up by Vertical, it’s available to purchase or rent on Apple TV+, and a limited theatrical release will come on Friday in theaters in Brooklyn, Chicago, Detroit and Long Beach.

It’s a powerful lead turn for Donovan, best-known to date for appearing on TV dramas like “Grey’s Anatomy” and the recent “Magnum, P.I.” reboot. The role required him not only to play two characters but to throw himself into the extreme emotional state of a man contending not only with the dissolution of his family but of his own reality.

The Marin IJ spoke to Donovan, who’s lived in Los Angeles since 2008 after studying acting at the University of North Carolina School of the Arts, about the challenges of the performances and the experience of stepping into such a challenging role.

Q What about the script stuck out to you when you first read it?

A I’ve read a lot of horror scripts, and generally you get the blood and the guts and the jump scares and all of that. This script stuck out because it was so character-driven. It lived in relationships and not in the gimmicks of horror. It’s horror with heart, and when I first read it, it had my heart pounding the whole time. It was a real page-turner, and reading for this role of Nicholas, it was pretty terrifying just because of the journey the character goes on. Stepping into this character’s shoes felt daunting. It deals heavily with grief, the loss of a child and the strains in a marriage, and also the psychological breakdown of reality. It’s a very emotionally demanding role, on top of having to play Nicholas and his doppelgänger, the Fetch. The lucky part was that by the time we shot, I had already been working on the role for three years and helping develop the character and the story with the writers and producers. By the time we got on set, it was a harmonious, coherent team who all had the same vision and supported each other.

Q Tell me about the challenges of playing a dual role.

A For this film, the big question for me was how we were going to match the tone of what we were going for. If we get really cartoony with the character, do we lose touch of the relationship and the grounded reality we’re trying to introduce to the audience? We’re making a horror film that needs to be entertaining, but not so far that it looks cheesy or gimmicky. It was also important to all of us that we represent mental illness in a different way. The movie is based on a schizophrenic condition, so the writers consulted with psychiatrists and wanted to vet the experience of this character based on the circumstances and what he’s going through.

Q Did you draw on any personal experiences from your life in this role?

A I didn’t have anything to do with the conception of a story, but as an actor, I find all my life experiences have allowed me to have a greater toolkit. I haven’t lost a child, but I know the feeling of loss from relatives passing or friends passing, and I had a bout with cancer myself. It’s just that foundational fear of not being in control of what’s happening to a certain extent in this life. We don’t have a culture that really looks at these things. I think the writers did a beautiful job of showing the gray spaces of the grief process and loss. As an actor, I live in a context where I need to think about these aspects of life — what is it about these things that are terrifying? How do I relate to that? I’ve been lucky in that I went to a great drama school in North Carolina and had great acting coaches in Marin and people saying, “You need to look deeper into what this is.” At a certain point, it’s not about acting techniques, it’s about relating to yourself, the world and people around you. That’s what you really draw from.

Q There have been a lot of movies with double roles lately — “Sinners,” “Mickey 17,” “The Monkey” and “The Alto Knights.” What do you think attracts people to the idea of doppelgängers and doubles?

A I do think it’s so interesting to see how when there’s one project coming out like that, inevitably there’s going to be a handful of others. No one’s really aware of what other people are doing. I can relate to it in that we live in a world where people want to put you in a box and they say, “Well, what do you do?” I’m an actor, but I’m also a portrait photographer.

It feels like we’re so multifaceted and we have so many sides. There’s an evil side of me and a good side of me. It speaks to the fact that we’re not all one thing.