 The Doctor speaks with the Gelth via Gwyneth in a séance, where they claim to be few in number following the Time War, and ask for the Rift to be widened, allowing the remaining Gelth to live in the corpses.However, after the Doctor discovers that the Gelth are in fact far more populous than first claimed, and intend to slaughter the human race to provide themselves with inhabitable corpses, Gwyneth sacrifices herself by causing a gas explosion, which seals the Rift and apparently kills the Gelth.The episode "Boom Town", set in modern-day Cardiff, revisits the Rift.