The whole school gets an anonymous text saying that they will play Truth or Dare and if they don't take Dare, their secrets will be revealed.
What happened to Phoebe's father?
Phoebe's secret comes out in the game. She slept with her sister's ex-boyfriend. When her sister Emma finds out, she starts drinking a lot of alcohol.
the bomb attack
Brandon takes Dare, he has to jump off the roof of a construction site, but he falls through the roof and dies.
At the hospital
Phoebe finds out what happened to her father. When Brandon was a child he played at his father's construction site. This led to her father's death.
The anonymous person places a bomb next to the restaurant where Eli Kleinfelter is, but Maeve and Knox are able to bring the bomb as far away as possible before it explodes.
Everything clears up and they find out that Phoebe's sister made a deal with the anonymous person. They wanted to help each other to destroy their enemies. That's why Brandon died and why the anonymous person placed a bomb near Eli.