“THE DARK TOWER VI: SONG OF SUSANNAH,” by Stephen King, Donald M. Grant/Scribner, New York, 2004, hardcover, 432 pages, $30.

Stephen King has returned again to his “Dark Tower” series, which is set in an alternate world – which, based on this new sixth book, “Song of Susannah,” is the land of dangling subplots.

In any series, a certain amount of carryover is essential to take the readers from Point A to Point B (or, in this case, Point E to Point F. But I digress). But, Steve, wrap something up already!

This fantasy series by the Bangor author, which has been more than 20 years in the making, follows the quest by Roland of Gilead to save The Dark Tower, the crumbling center of civilization in Mid-World. Roland is aided by his ka-tet (or band bound together by fate) of gunslingers: the teen boy Jake Chambers and his pet Oy, the couple Eddie and Susannah Dean and Donald Callahan, a new addition from last year’s fifth book, “Wolves of the Calla” (and an alumnus of King’s book “Salem’s Lot.”)

“Wolves of the Calla” was a briskly moving, very satisfying read. It offered both forward momentum and needed back-story about this sprawling fantasy Western, as well as at least some degree of resolution. In “Song of Susannah,” not so much.

The new novel picks up, logically enough, where “Wolves of the Calla” left off. The remaining members of the ka-tet divide into two teams, each charged with a mission crucial to the fulfillment of the band’s quest.

Along the way, new characters are introduced and are foreshadowed as important pieces of King’s sprawling puzzle. These include King himself, making a cameo in print this time. And yes, there’s action, grotesque creatures and humor, and important secrets are revealed.

And yet, the suspense master takes readers right over the edge like lemmings, then leaves them hanging, waiting for the seventh book in the series, which is due out Sept. 21. So “Song of Susannah” will strike a sour note with those who like an actual ending when a book is done.