This is one of Pratchett’s very early novels and one of his few pure SF ones. Kin Arad is a planetary engineer and when an invisible man walks into her office with tales of a flat planet on the edge of known space, she is intrigued. Along with a four armed warrior Kung and a linguist Shandi they travel to the disc and what they learn changes the universe forever.
I found myself really enjoying this book, particularly the central idea of building entire worlds with their own faked history using technology salvaged from dead alien races, each of which indelibly stamps its mark on the universe. Although the second half on the disc itself seems at odds with this, the mystery of the disc itself, and who created it is a strong one, and sustains the book until the final twist where everything comes full circle. A great read.
