True crime is all the rage these days. Books, movies, documentaries, streaming series, podcasts — even streaming series about podcasts — are everywhere as Americans continue to obsess over the genre.

Author Casey Sherman is no stranger to true crime, having penned books about mobster Whitey Bulger, the Boston Strangler and the assassination of John Lennon.

Sherman, who grew up on Cape Cod, returns to both his true crime roots and hometown with his latest written effort.

“Helltown: The Untold Story of a Serial Killer on Cape Cod” focuses on the case of Antone “Tony” Costa, a counterculture figure who was convicted of murdering two Providence, Rhode Island, women in 1969, and is suspected in at least two other slayings in the Massachusetts tourist hotspot.

The Costa case was sensational at the time due to the grotesque nature of the killings that took place in such an idyllic setting — authorities say Costa had sex with the corpses, cut them into pieces and buried the remains in holes he dug in a wooded area. But it was quickly eclipsed in notoriety later that year when followers of another counterculture guru, Charles Manson, slaughtered pregnant actress Sharon Tate and six others in southern California.

While much has been written about Manson and his “family,” Sherman shines a light on the less well-known Costa killings, and he does so in a unique and compelling way.

“‘Helltown’ is a work of fact told with elements of fiction storytelling,” Sherman writes in the author’s note, adding that he had “never married journalism with narrative storytelling before.”

And he does so to great effect. “Helltown” — the nickname given to the Cape Cod community of Provincetown in the 1600s due to drinking, gambling and other vices common at the time — reads like a novel.

Sherman places readers not only on the Cape before, during and after the murders, but he puts them inside Costa’s troubled mind. And he beautifully develops a host of characters beyond the killer, including Costa’s “disciples,” the police who eventually discover his wrongdoing and the lawyers who battle it out during the 1970 murder trial. Not to mention American literary icons Norman Mailer and Kurt Vonnegut, both Cape Cod residents who find themselves fascinated by Costa’s brutality.

The whodunit portion of the book is perhaps the most potent. First, as law enforcement tries to figure out what happened to the missing 23-year-old friends, Patricia Walsh and Mary Ann Wysocki, an elementary school teacher and college student, respectively, who were visiting Provincetown for the weekend. And later, the cat-and-mouse game between police and Costa following the gruesome discovery of their bodies.

“Helltown” is an immersive and captivating journey into the mind of a serial killer. Sherman relied in part on an unpublished manuscript written by Costa, who hanged himself in a Massachusetts prison in 1974.

“The majority of what you read here really happened, sadly,” Sherman writes.

And is laid out in such a way that should satisfy most true crime aficionados.