Grace's father was on a private jet that crashed, we still didn't learn whether it was an accident, suicide, or murder. more likely the first 2. Grace refused to call him before he left to get on the plane, because she was mad about his veiws on her having sex. Her and Jack have sex that night, and when her mother and Tom return home from dropping him off at the airport, they are in tears. The mother tells Jack, then grace comes in and she tells her, and then Tom says "You killed him". Then it pans out to all the other characters finding out through their parents. Adriannes mother was not on board, she is fine.
Watched it tonight. Email me if you want more details.