To Green Angel Tower is the third and final novel in Tad Williams' Memory, Sorrow, and Thorn trilogy. At over 520,000 words, it is one of the longest novels ever written. Due to the length of the novel, the paperback version had to be split into two separate volumes, known as To Green Angel Tower: Part 1 and Part 2. In the United Kingdom, the two paperback volumes were titled To Green Angel Tower: Siege and To Green Angel Tower: Storm. The saga follows a young man named Simon as he is caught up in an epic adventure. Source: Wikipedia (en)