Quarra was a heavily industrialized M-class planet located in the Delta Quadrant. It was home to the warp-capable Quarren, as well as a large immigrant population of species from other worlds. The planet was protected by patrol ships and a shield grid that prevented transporter use.
In 2377, Quarra and the rest of its star system were suffering from a severe labor shortage, causing intense competition for workers. Unlike the other planets in the system, guest workers on Quarra were granted full legal protections. During this time, residents were subject to a curfew.
The demand for skilled workers led to the formation of a criminal conspiracy, in which Quarren coyote ships would attack alien starships and abduct their crews. Doctor Kadan at the Central Hospital would then alter the abductees' memories to make them believe they willingly came to Quarra in search of a job that had been prearranged for them.
Several thousand people were illegally added to Quarra's workforce in this fashion, including most of the crew of USS Voyager. Commander Chakotay, Ensign Harry Kim, and the Doctor were able to expose the conspiracy with help from Yerid of Criminal Investigations. The Quarren authorities promised that all of Kadan's victims would be treated and repatriated. (VOY: "Workforce", "Workforce, Part II")