Míriam is expecting her second child. Her marriage isn't all that great and, because she is at risk of giving birth prematurely, doctors have prescribed complete bed rest. Her husband is caught up in his work at the publishing house and has no time to spend with her. Míriam tries to escape the tedium of her confinement, alone in the house, by reading crime novels and spying on her new neighbours, Juan and Sara, a young couple recently arrived in Madrid. As the days pass, a series of strange events leads Míriam to suspect that the couple has something to hide. Her husband accuses her of being paranoid, but she is determined to get to the bottom of the mystery. As the plot thickens, Cristian finds himself taking over the investigation where his wife had left it.