The one where the series becomes itself.
No dark lord, no prophecy. The plot is a wrongful conviction and a man who has been in prison for twelve years for something he did not do, which is a sharper idea than anything in the first two books.
The time travel in the last act is handled better than most adult fiction manages, because it is closed and consistent and the reader has already watched the effects before being shown the causes.
Read June 2020.