In 1985, Dorothy Lou Thompson disappeared from her home on the grounds of the pet cemetery she ran in the bayou outside New Orleans. Her body later turned up in the Mississippi River, wrapped in chains. The case went cold for decades, until a witness came forward claiming Dorothy's ghost had pushed him to talk. That's the story behind HBO's The Pet Cemetery Murders: A Ghost Story, a three-part docuseries from director Philip Cairney that premieres Oct. 11.

Read on for everything to know, including the trailer, premiere date, and episode guide.

"How do you lose a person?" one voice asks, as investigators recall finding Dorothy Thompson's home empty with no sign of a struggle. From there it moves to the discovery of her body in the Mississippi and a phone call in 2009 from a man with information about an old murder at the pet cemetery. "It was her ghost that I saw," he says. The trailer closes with a warning that the case keeps on twisting: "When you think the story's over, something else always comes up."

The series starts with Dorothy Thompson's disappearance and the land her pet cemetery sat on, which locals had long believed was cursed. With no concrete evidence, the case stalled until Det. John Doran reopened the investigation and started going back through the old leads. Then a witness came forward with a story about Dorothy's ghost, and three years later a second witness said he was being haunted by her too. Their accounts sent investigators digging into Dorothy's past, which turned up a trail of dead husbands, a domineering mother named Grace who founded the cemetery after running from her own crimes, and a community with a long history of violence.

The Pet Cemetery Murders premieres Oct. 11 at 9 p.m. ET/PT on HBO and HBO Max, with new episodes weekly on Sundays through the Oct. 25 finale.

Episode 1: Oct. 11, 9 p.m. ET/PT (46 minutes)
A decades-old Louisiana cold case involving the gruesome death of pet cemetery owner Dorothy Lou Thompson gains traction when a startling account sends investigators down a series of haunting leads.

Episode 2: Oct. 18, 9 p.m. ET/PT (43 minutes)
Detectives make progress on Dorothy's case, and an unlikely witness comes forward with a troubling admission.

Episode 3: Oct. 25, 9 p.m. ET/PT (53 minutes)
Dorothy's murder is solved, but the case has uncovered a trail of murders, mobsters, and a horrific history that still haunts the community.

Dorothy's friends, family, and neighbors, along with law enforcement officers, historians, artists, journalists, and attorneys.

Cairney (Being Beethoven) directed and wrote the series for Lightbox, the company run by Oscar winner Simon Chinn and Emmy winner Jonathan Chinn (The Princess, Tina). The executive producers are Simon Chinn, Jonathan Chinn, Suzanne Lavery, James Marsh, and Silvia Sacco, with Nancy Abraham, Lisa Heller, and Tina Nguyen executive producing for HBO.