Winslet, who's also an executive producer, plays Mare Sheehan, whose life is crumbling around her as she investigates a murder.
Nicholson, who's coming off Netflix's Blonde and HBO's The Outsider, plays Lori Ross, Mare's best friend since childhood. She knows how mercurial Mare can be but loves and accepts her as she is.
Smart plays Mare's mother, Helen. Stubborn, opinionated and a devout Catholic, Helen never holds back on her opinions, whether they're solicited or not.
Rice will play Siobhan, Mare and Frank's (Denman) daughter, a lovely, brilliant young woman who's also rebellious and strong headed.
David Denman's Frank is an affable math teacher at the local high school. He and Mare got married at age 20 but split up years ago.
Peters will play Colin Zabel, a county detective called in to help with Mare's investigation, much to her chagrin.
Spaeny rounds out the group as Erin McMenamin, a lonely teen who lives with her volatile father and the only love in her life, infant son DJ.
Creator Brad Ingelsby (Run All Night, American Woman) is writing every episode and will serve as showrunner, and Gavin O'Connor (The Accountant) will direct the entire project. They executive produce with Winslet, Gordon Gray and Paul Lee and Mark Roybal of wiip. The series is a co-production of HBO and wiip.