What if everything you remember is a lie?

Freya Izquierdo and Fletcher Cohen believe they're done with top-secret memory knifing. After successfully hacking a terrorist's memories and foiling the Memory Ghosts' next attack, they spend their school break intending to clear Fletcher's dad of being accused of colluding with the radical group.

Exposing the truth should be straightforward, if not easy. But Fletcher's house is robbed, and Freya makes a shocking discovery about her flawed recall. When they return to Foxtail Academy, no one but the dean and Dr. Sanders seems to remember Freya, Fletcher, and their friends Chase and Ollie. Then the Memory Ghosts make contact, and everything the four students thought was true proves false.

As they struggle to shine light on the shadowy battlefield between Memory Frontier and the Memory Ghosts, their only option is to undertake the most difficult and risky knifing mission of their lives. But this time, more than their lives are at stake.

In this heart-stopping and gripping conclusion to the critically acclaimed Memory Index duology, the only way out is in, and the only way to safety is through reckless danger that could wipe Freya and Fletcher from everyone's minds . . . forever.