Over the next 17 years, Gandalf travels extensively, searching for answers on the ring. He finds some answers in Isildur's scroll, in the archives of Minas Tirith. He also wants to question Gollum, who had borne the ring for many years. Gandalf searches long and hard for Gollum, and often has the assistance of Aragorn. Aragorn eventually succeeds in finding Gollum. Gandalf questions Gollum, threatening him with fire when he proves unwilling to speak. Gandalf learns that Sauron has forced Gollum under torture in Barad-dûr to tell what he knows of the ring. This reinforces Gandalf's growing suspicion that Bilbo's ring is the One Ring.