Gandalf knew that Smaug the dragon could pose a serious threat if used by Sauron, then dwelling in Dol Guldur in Mirkwood. He was thinking about the matter when he met Thorin Oakenshield at Bree. Thorin too was concerned about Smaug, but had different motives: he wanted to reclaim the dwarves' treasure in the Lonely Mountain. Gandalf agreed to help Thorin, though he insisted that his party must make use of stealth rather than open confrontation; for that, they would need a burglar, to whom he would take them.