Part I (Season 4)

"Part I" is the first episode of the fourth season of The Sinner.

Synopsis
During a getaway with Sonya in Maine, Ambrose finds himself plagued by insomnia. On a late-night walk, he witnesses a young woman step off a cliff.

Cast

 * Bill Pullman as Harry Ambrose
 * Alice Kremelberg as Percy Muldoon
 * Frances Fisher as Meg Muldoon
 * Neal Huff as Sean Muldoon
 * Cindy Cheung as Stephanie Lam
 * Ronin Wong as Mike Lam
 * Jessica Hecht as Sonya Barzel
 * Michael Mosley as Colin Muldoon