Sinner, The (TV Series)

Aroview: An 8-episode miniseries starring Jessica Biel as a seemingly ordinary woman who brutally murders someone out of nowhere during a trip to the beach. She immediately pleads guilty, but neither her nor the detective in charge (Bill Pullman) can figure out what the cause was. An unusual "whydunnit" premise, starting with a single horrific act and leading towards a satisfying and gripping conclusion.