In Stephen King’s novel The Waste Lands, the ka-tet finds Blaine the Mono in the city of Lud.
Lud is a ruined, dangerous city in Mid-World. Roland Deschain and his companions enter it while pursuing the path of the Beam, and their journey eventually brings them to Blaine, a sentient monorail with a fondness for riddles and a deadly bargain.
The Waste Lands is the third novel in The Dark Tower series and was published in 1991. Its plot expands the series’ world beyond the desert landscapes of the first two books, introducing major locations, characters, and the concept of the ka-tet as a group bound together by destiny.
Lud is not the same place as Gilead, Roland’s lost home, or Calla Bryn Sturgis, a later setting in the series. Those names belong to different locations in the Dark Tower universe.