Tilonus IV is a Class M planet, home to a humanoid civilization with high curved forehead arches. . The government of Tilonus IV was in a state of total anarchy when Commander William Riker attempted to rescue a Federation research team there in 2369. He was captured by one of the factions and subjected to neural manipulation at the Tilonus Institute for Mental Disorders, by Dr. Syrus, in an attempt to extract tactical information from him (TNG: "Frame of Mind").
Advertisement