There’s no mystery surrounding how “I Am the Night,” TNT’s new truthy-crime mini-series, came to be. The director Patty Jenkins met and befriended Fauna Hodel, author of a memoir, “One Day She’ll Darken,” about her difficult youth. Not quite a decade later Jenkins made “Wonder Woman,” which made more than $821 million. Et voilà: “I Am the Night,” a long-gestating project “inspired by the life of Fauna Hodel” with Jenkins as a director and executive producer.

It’s less clear how the six-episode mini-series (beginning Monday), which was created and written by Jenkins’s husband, Sam Sheridan, and stars her “Wonder Woman” collaborator Chris Pine, turned out to be such a lackluster and derivative affair. But we can speculate.

Hodel’s book was primarily the story of her childhood and teenage years, when she grew up with African-American adoptive parents and thought she was mixed-race, although she was white. It had a sensational kicker: When she learned the truth about her biological parents, she also learned that one of her grandfathers was George Hodel, a prime suspect in the infamously gruesome and unsolved Black Dahlia killing in 1947.

So the story had two currently hot hooks: struggles with race and identity, on one hand, and a lurid real-life murder mystery, on the other. It was out of balance — George Hodel and the Black Dahlia case were a minor, if highly promotable, part of the book — but screenwriting could fix that.