Patternmaster is after the Octavia Butler’s intentionally “unpublished” Survior book (Patternmaster #4) So you read “Clay’s Ark” (#3) then on to Patternmaster (#5). (Survivor can be obtained… I have it, just didn’t read it. If Octavia hated it and didn’t want it in the series, I figure she would be the best advisor on the series)
Patternmaster is a considerable jump into the future of the series, chronologically. Clay’s Ark, the previous book establishes that time jump. In this conclusion of the series, every character you have connected with previously in the series is “history.” Just back story and not much relevant except YOU would know it.
The “Patternmaster” established in Mind of My Mind has evolved with even more zeal than Doro, (Wild Seed, Mind of My Mind) ever imagined. Doro’s evolved plans, carried on by “Mary” has swept the globe… with the exception of the Clay’s Ark “issue” which has become a war with another segment of the devolved/evolved species of humans. While this “Clay’s Ark Humans” vs “Patternmaster” people is a subplot is it barely worth noticing.
Another issue that would have been an interesting sub-plot, possibly even another book or series from another perspective, are the “mutes”. A mute would be Johnny in Battlefield Earth (L. Ron Hubbard). Or “You” of here and now, in a world where the human species have not split into three different sub-species of humans. “Mutes” are powerless over both Patternists and Clay’s Ark people. Slaves of one or victims of the other.
I recommend the book as it is the conclusion of the series and most folks want to know how it ends if they’ve already invested in several previous books.
Truth is, I think you could stop after Mind of My Mind. You would still be hungry for more of that story, but the remainder of the series doesn’t really feed much of that hunger. Clay’s Ark is like a side trip that is almost irrelevant side show in Patternmaster which is mostly a power struggle over the evolution of Mary’s “gift” in Mind of My Mind. I say… think Game of Thrones, without the extensive detail or drama.