Antonia Scott is the most intelligent woman in the world –a virtue and a curse at the same time. Her intelligence allowed her to become the "Red Queen" of a secret experimental police project. But a personal tragedy removed her from active duty. Now, Jon Gutiérrez, a police officer in trouble, has to get her out of her seclusion to solve a case that will put her abilities and her past to the test.

Ezequiel has assassinated Álvaro Trueba and has kidnapped Carla Ortiz, both the firstborn of the most powerful families in Spain. Jon agrees to be Antonia's squire. Even though they started off with the wrong foot, they're about to catch Ezequiel after a fast-paced chase that has everyone on edge. In her cell, Carla finds out that she is not Ezequiel's only prisoner.

Antonia and Jon have barely started and they have already got the Kidnapping Unit, Ramón Ortiz, Laura Trueba and the shadow leader of Reina Roja, Mentor, against them. During the course of the investigation, everyone lies. Antonia and Jon realize that what Ezequiel has asked of Ortiz and Trueba is an admission of guilt. But Ezequiel is always one step ahead and now his threat looms over Antonia.

Antonia wakes up alone facing a mural. Why didn't Ezequiel kill her? The assassin wanted to deliver a message. A message that leads Antonia and Jon to a taxi car and to discover the true identity behind Ezequiel. The Kidnapping Unit has also found Ezequiel's address and taxi car, but Antonia notices that the pieces don't fit together as neatly...

Antonia and Jon find out Ezequiel's daughter is helping him, but things don't add up. They have committed too many mistakes. But when the Kidnapping Unit falls into a trap, they realize they weren't mistakes. Carla discovers the truth about the kidnapped woman in the other cell. Jon makes a blunder that causes Mentor to close the case and remove Antonia from her position as the Spanish Red Queen.