This is one Hamptons festival that isn’t too cool for ghoul.

A Long Island “mystery and crime” festival that focuses on the elusive Gilgo Beach serial killer is being blasted as “heartless and misogynistic” for exploiting the brutal killings of young women and sex workers.

The inaugural “Hamptons Whodunit” festival kicks off in April and promises to explore the notorious string of unsolved murders through a moderated panel with former NYPD homicide investigator Joe Giacalone and filmmaker Josh Zeman.

“Calling this a festival is kinda sick,” said one local, while another deadpanned: “Oh a murder festival. How quaint.”

The hour-long panel, “The Elusive Long Island Serial Killer: Gilgo,” will focus on the remains of 10 different people, four of whom were identified as female sex workers, discovered beginning in 2010 on Gilgo and Oak Beach in Suffolk County.

The April 13 – 16 event, billed as “an exciting weekend that will chill you to the bone,” also touts an “exclusive” $75 cocktail party at the “iconic” upper-crust Maidstone Club in East Hampton.

The event website promises you’ll “join Professor Plum for wine, cocktails and hors d’oeuvres,” while the dress code bans what’s “not considered appropriate attire”: jeans, sneakers, collarless shirts, and shorts.

Despite the posh soirees, one of the organizers insisted that they were focused on “finding justice and finding the killers who committed these atrocities.”

“We have an eclectic range of participants – some of our moderators had family members who were murdered – and we don’t take lightly that there’s some tough content, but we do it with respect,” said Carrie Doyle, festival co-organizer and Trustee of East Hampton Village.

A co-sponsor of the festival, Hamptons publication Dan’s Papers, has faced a barrage of outrage from locals on social media.

“I’m undone by the crude and uncaring sentiment to the crimes against Women that is somehow marketed as entertainment,” one West Hamptonite wrote.

“This whole enterprise is disappointing, coarse and seethingly misogynistic. A ‘festival’ based on the death of Women is absolutely heartless and cruel.”

But Zeman, the filmmaker, argued that the Gilgo session was not intended to minimize the horror but keep the brutal murders in the public eye and fuel the investigation.

“This is in no way a celebration of such tragedies, but an opportunity for us to come together,” said Zeman, who directed A&E’s “The Killing Season,” a docuseries about the Gilgo Beach murders.

“It’s a place where [we] congregate to delve into these stories. I think we need to take advantage of any opportunity to keep this story in the public eye… and get these cases the attention they deserve.”