When Angels Sleep is a story about Germán, a CEO of a life insurance company who is too busy with his job to attend to his personal life with his wife Sandra and his daughter Estela.
Trying to make it home in time for Estela's birthday party, Germán is stopped by two Civil Guard agents who notice his extreme exhaustion. They guide him to a motel to rest and prevent an accident.
Meanwhile, Silvia, a troubled teen, runs away from her troubled home to meet her friend Gloria and ends up spending the night with Mario and El Chato in Mario's car.
As Germán eludes the Civil Guard agents and heads home, Silvia rejects El Chato's advances and leaves the car with Gloria. Unfortunately, Gloria is run over by an asleep Germán while Silvia is hiding.
When Germán wakes up and finds the injured Gloria and a shocked Silvia, he tries to help them by taking them to the hospital. Sandra tries to locate Germán, while Mario and El Chato seek revenge on the girls.
As Silvia believes Germán tried to kill them on purpose, she fights him and runs away. Germán, fearing losing his family and going to jail, pursues Silvia to change her mind.
They all experience a fearful night where everything that can go wrong, does go very wrong.