Alex Grass thinks that, on some level, he was always destined to become a horror novelist. “Everything makes sense now,” he says. “When I was in the midst of it, it did not.”

His path to becoming a novelist included time in law school, a passion for weightlifting, and a close relationship with his family, especially his three younger brothers. The four boys had a sense of adventure and a taste for pranks that reached a level Grass calls “legal system bad,” like the time they borrowed an Israeli border patrol vehicle. “You look back on it and say wow, how did we become adults?” he admits.

Having successfully reached adulthood, Grass has channeled his boundary-pushing instincts into A Boy’s Hammer, which blends Finnish mythology and the police procedural. Alan, thought to have been dead for decades, has actually been fighting his way through the underworld, and he returns to his home in Philadelphia to try to reconnect with friends and family. At the same time, the city is being terrorized by a serial killer and is also facing supernatural threats, and police officer Jefferson O’Brady has to fight his own demons while solving the mysteries. “Along with the genre elements and bombshell-laden storyline, the richly described worldbuilding helps create a wildly immersive read,” Kirkus Reviews writes.

Grass vividly describes the underworld Alan escapes from:

Alan did sometimes find other sentient creatures, vapors and mists outlining an ectoplasmic silhouette, a being impossible to retain in shape and bereft of its spirit’s memories. These non-malevolent creatures were his sort, trapped just like him in this hellscape. These less-demonic beings spoke to Alan, told him that he was a prisoner of Tuonela. That’s what this land was called. There were different levels to Tuonela—Alan was far down at this point, after so many deaths. But on that abysmal level, he was a champion. He could go and do as he pleased. The monsters were long ago outmatched. Now there was this warren of nightmares whose very existence breathed decomposition and damnation. What was left but to explore it?

Grass decided to write about Finnish mythology after seeing the painting The Defense of the Sampo, by Akseli Gallen-Kallela. “It sent me into a tizzy. I had to find out who had painted this and why,” he says. “There’s something incredibly modern about it, but there’s a hint of the primordial.” His research into the painting’s backstory led him to the world of Elias Lönnrot, who compiled the country’s oral traditions during the 19th century, publishing them as the Kalevala, an epic poem, which served as the inspiration for the world of A Boy’s Hammer. 

This is Grass’ fourth horror novel. He read Stephen King when he was younger—Cujo was an early favorite—but had moved away from the genre in adulthood. He pursued other interests, some of which were not necessarily sustainable. “I was the headbanging, whiskey-swigging, coke-snorting, rip-roaring party guy,” he says. “There was no place I’d rather be than a dive bar.” As his years of hard living caught up with him, Grass found himself moving in a new direction. “The real reason I came to writing was because so many years of that stuff—basically, it was about to tear everything apart,” he says. 

A stint in rehab brought him back to King, and he read Doctor Sleep at a pivotal moment in his recovery. “Someone took my soul and put it into the washer and dryer, and it came out and it was just different,” he says. Doctor Sleep, “straddling the line between horror and dark fantasy, horror and urban fantasy, horror and science fiction,” and telling the story of a man who “set aside this life he was predetermined to have,” brought him clarity.

Grass, who lives in Brooklyn, combines his writing with taking care of his three children, and he says that writing while parenting is more about survival than balance. He doesn’t write every day but creates his books in sprints. “When I write, there’s just a month of terribly unhealthy living,” with late nights at the keyboard fueled by lots of coffee and nicotine and followed by early-morning school drop-offs. “The writing is fun. I really enjoy it. It’s physically very wearing,” he says, but his family obligations come first. “I don’t want my family to think I have a priority above them.” The core of his approach to writing and life, he says, is, “you give it your best shot, and you ask the people you love to remind you if you’re being an ass.”

“In the beginning when you write something, you have no idea if it’s going to work,” Grass says. He started out with the goal of finding “one person to read one of my books the way I read Stephen King,” and he was happy to start hearing from readers after publishing his first book. “It’s really important to me to talk to them,” he says.

“You talk to people, and you learn a lot that you [thought] you knew,” says Grass, who has enjoyed learning that his assumptions about the demographics of his readers were off. “I had a misinformed idea that horror readers would be dudes between 20 and 40, and that was completely wrong,” he says. Instead, “there’s not a type, which I thought was cool.” Many of his fans are decades older than he is. One tells him about sharing his books with her grandson. Another is a widower who has read every book Grass has written and has stayed in touch with him throughout his career. “They’ve been through life, and they look at something I wrote, and they think it’s decent,” he says. “I don’t assume there’ll be some crazy commercial success or anything like that, but it’s neat to think of having these connections with people who are in with you from the beginning.”

Sarah Rettger is a writer and bookseller in Massachusetts.