After years in isolation, Ulises returns to Barcelona when his former partner asks for help decrypting Pandora, the code behind a revolutionary technology. The reunion ends in murder, turning Ulises into the main suspect. As a video of his escape goes viral, tech mogul Damián Diskin prepares to launch Day One, and Ulises realizes that nothing - not even his friend's death - is what it seems.

With no trace of Pandora, Ulises turns to Paula, who shows him another video revealing the killer. The only person who can clear him is Rebeca, whose social media activity puts her in Diskin's sights. Determined to protect the launch of Day One, Diskin intervenes through the technology itself, erasing evidence and sending a mercenary to silence all witnesses.

Ulises goes into hiding with Rebeca, the only witness who can prove his innocence. Together they discover where Pandora may be hidden, but Rebeca secretly activates the technology, exposing their location. Diskin sends his mercenary to close all loose ends. As violence erupts, Ulises loses everything and is forced to run once again.

Rebeca is questioned by the police while Ulises becomes the prime suspect in another murder. When they reunite, they finally access Pandora and uncover its true nature. Unaware that she is being controlled through the contact lenses, Rebeca exposes their location. Biran heads toward their location, as both the police and Diskin close in.

Ulises and Rebeca go to the Synchrotron. They need the power of the accelerator to obtain definitive proof that could stop 'Day One'. When they activate the contact lenses to infiltrate the facility, Diskin tracks them. A chase erupts inside the accelerator. Separated and cornered, Ulises escapes outside, where he comes face to face with Inspector Moreno, who aims... and fires.

Ulises and Rebeca are taken to Diskin's headquarters under the threat of Inspector Moreno. Meanwhile, Beth considers betraying the magnate and seeks Salvador's help. Diskin reveals the true purpose of the lenses and asks Ulises for his collaboration. As the global launch begins, evidence of the technology's danger breaks into the live broadcast, exposing the truth.