Fifty Fifty

Two sisters on trial for murder. They accuse each other. Who do you believe? From Steve Cavanagh, the "wickedly clever" (The New York Times) master of twisty psychological thrillers."911 what's your emergency?" "My dad's dead. My sister Sofia killed him. She's still in the house. Please send help." "My dad's dead. My sister Alexandra killed him. She's still in the house. Please send help." One of them is a liar and a killer. But which one?