In 2369, after the assassination of the Prime Minister, the government of Tilonus IV collapsed. The remnants of the government splintered into factions that were vying for control and were desperately looking for a technological or weapon that would aid them in their cause. Some factions resorted to torture. As the internecine fighting spread, the civilization was in total anarchy. Fearing for their safety, a Federation research team on the planet went into hiding.
Aboard the USS Enterprise-D, Captain Jean-Luc Picard ordered Commander William T. Riker to rescue the Federation research team there. He was captured by one of the factions and subjected to neural manipulation by Suna at the Tilonus Institute for Mental Disorders in an attempt to extract strategic information from him. (TNG: "Frame of Mind")