Gruesome details Michael (Colin Firth) and Kathleen (Toni Collette) were carousing by their pool after dinner, drinking wine, when Kathleen went back inside their mansion. Michael claims he returned ...

“The Staircase," which debuts Thursday, shifts more of its focus from Michael (Colin Firth) to Kathleen (Toni Collette) and the other family members involved in the murder case.