Psychonauts in the Rhombus of Ruin is a first-person virtual reality puzzle platform video game. The game's story is intended to bridge the events between Psychonauts and Psychonauts 2.

At the end of Psychonauts, Raz is recognized as a great PSI Cadet and is asked to join his tutors as a fully fledged Psychonaut. But as Raz prepares to go home from camp with his father, news arrives that the Grand Head of the Psychonauts (and Lili's father) Truman Zanotto, has been kidnapped. The team, Raz and Lili included, fly off in the Psychonauts' jet to rescue him.