Mickey (Amanda Seyfried), a Philadelphia police officer, suspects a serial killer is targeting young women on “The Long Bright River.” PEACOCK Share When Amanda Seyfried was on “The Tonight Show Starring Jimmy Fallon” last week,

Since bursting onto the scene more than two decades ago in Mean Girls, Seyfried has become one of Hollywood’s most reliable supporting actors. But with her Emmy- and Golden Globe-winning portrayal of disgraced Theranos founder Elizabeth Holmes in The Dropout and now an outstanding turn as a hardened cop in Long Bright River,