“I’ll let it go when I find her.”

Amanda Seyfried’s new thriller series Long Bright River has released a first trailer, unveiling a connection between the protagonist and a series of brutal murders.

Based on Liz Moore’s 2020 bestseller of the same name, Long Bright River features the Mamma Mia! star as Mickey Fitzpatrick, a patrol cop working in a Philadelphia neighbourhood plagued by the opioid crisis.

The trailer sees Mickey going above her pay grade when she starts looking into a streak of homicides targeting women in the area. As she investigates, Mickey fears the killings may hit close to home and that her younger sister Kacey, who has disappeared, could be next.

Soundtracked to an eerie rendition of ‘Lovesong’ by The Cure, the clip follows Mickey as she vows to protect the women working on the streets from whoever is going after them.

Meanwhile, she grows uneasy as she experiences visions of Kacey and realises the killer could be someone she knows. Digging deeper into the three murders, Mickey is taken aback when she spots the same red pickup truck her sister was last seen in just outside her house.

“I’ll let it go when I find her,” Mickey finally tells another character who suggests she give up her search.

Written and executive produced by Moore and Nikki Toscano, who was the co-showrunner of Hunters on Prime Video, Long Bright River also stars Nicholas Pinnock, Ashleigh Cummings, Callum Vinson and John Doman.

Speaking in a joint statement when the series was announced last year, Moore and Toscano said: “We are thrilled that Amanda Seyfried will lead this series about how those initially perceived as victims can band together to regain their power.

“Moore’s family history and her work with harm-reduction and community-service organisations in Philadelphia informed the series, which aims to portray with compassion the lives of those struggling with addiction and the family members who love them.”

Long Bright River will start streaming on Peacock in the US on March 13.