In volume two of the Dark Tower saga Roland wakes up 10 years after the vision which closed the first book. The Man in Black, with whom he shared the vision, is in much worst shape, having apparently experienced subjective centuries. In very short order the Gunslinger loses two fingers and a toe to monster lobsters that come in with the tide to feed and finds himself handicapped in his quest for the tower.
Driven by the vision and his obsession, he seeks the partners he needs to complete his quest. This involves three forays into our world, gained through mystic portals which allow him to cohabit the psyches of the individuals whom fate has chosen to join him. Most of this book is about how he meets them, and how they come across into mid-world.
Eddie is a heroin addict in New York of 1987 when Roland encounters him. Susanna is a schizoid crippled woman from 1963 whose mind is divided between the cultured, prudish Odetta and the hard case Detta.
A third door takes Roland into the mind of Jack Mort, a madman whose life has intersected both Susannaís and a boy, Jake, who we met in the first book. Rolandís actions then change the timeline and lead to problems which will become more important in book three.
In the meantime, book two is the fascinating story of how these three begin to function as a unit, a ka-tet, in Rolandís High Tongue, and how the reluctant imports adapt to life in Rolandís Mid-World.