The Manchester, UK, terror attack this past May eerily mirrored a similar event in Stephen King’s novel “Mr. Mercedes.” Producers behind Audience Network’s upcoming adaptation of the novel confirmed that they changed that central event for the series, in a way that won’t be revealed here.

At Tuesday’s Television Critics Association press tour panel for the series, director Jack Bender said that the show’s choice to change that framework was decided early on and was a “better way to make it a potentially more catastrophic event.”

On May 22, a young male suicide bomber walked into the foyer of the Ariana Grande concert in Manchester Arena and detonated a nail bomb that he had strapped to himself, killing 22 people (one child as young as 8 years old) and injuring 250. In the novel “Mr. Mercedes,” the killer Brady Hartsfield, who is being pursued by detective Bill Hodges, also...