A missing woman with a journal implicating her husband. An alcoholic ex-wife who can't quite piece together her involvement in a murder. A British mother who returns to the police force to hunt down a serial killer from her past, but can't explain her own blackouts and violent outbursts.You're no doubt familiar with Gone Girl's Amy Dunne and The Girl on the Train's Rachel Watson. Today marks the U.S. debut of that third female character, Detective Sergeant Marcella Backland, the protagonist — we think — of Netflix's Marcella.Available to stream today, the British crime thriller sees Anna Friel playing the title character with dogged determination undercut with a sizzle of anxiety and raw brutalism. The episode begins with her jolting awake to find herself soaking in the tub, her hair matted with blood. She sobs, but we don't know why. Is the blood hers or someone else's? Is she a killer or the victim of her own imagination?Thanks to a disorder that causes memory blackouts, not even Marcella can say for sure. One minute she's the loose-cannon detective showing her police colleagues just how foolish and wrong they are about a suspect; the next she's unraveling at the seams, pushing her philandering husband down the stairs and tearing up the bathroom at work. She's the doting mom at the school talent show, but also the rejected wife who can't remember just how far she's taken things.It all makes for compelling, fingernail-chewing drama, of course. It hasn't escaped our attention, however, that Marcella is just one of many female narrators who seem unreliable and, by default, unstable. Gone Girl has spawned an entire genre of shady-seeming "protagonists," with The Luckiest Girl Alive and All the Missing Girls among its latest representatives.TV, too, has delved into the theme of women with murky motives and complicated pasts (see: Homeland's Carrie Mathison, How to Get Away with Murder's Annalise Keating, and The Bridge's Saga Norén), but the passionate pursuit of their careers seemed to trump all else. Marcella Backland shares that drive. It's her blackouts and bouts of rage that hint at something more sinister, more culpable. Is she a hero or a horror?This is a meaty role any actress would love to sink her teeth into. We'd be lying if we said it wasn't refreshing to see women cast in complicated lead roles that challenge our sense of black and white, hero and villain. Are we also wary that this "unstable female" trope will wear thin? Absolutely. For now, though, we'll be binge-watching with the best of them.