Caught the preview last night. It's about a detective who gets into a car accident with his wife and son. After the accident, he lives in two worlds. In one his wife dies and his son survives. In the other one, his son dies but his wife survives.
It's supposed to premier March 1st but the first episode in online on hulu and I'm assuming nbc.com. It's also on NBC's on-demand channel on Verizon.