William F. Nolan 
Logan’s Run: Black Flower #4 [EPUB ebook] 

Twenty-one years. That’s all we get. But not those who have found Sanctuary and not those who control the secret of Hourglass. Logan finally challenges Gant in an epic showdown for control of not just Hourglass, but the all-powerful Thinker. But it’s more than just time clocks at stake. It’s Jessica too. The concluding chapter of this sprawling and thoughtful adventure of what happens when a society simply uses and never builds comes down to this clash of two titanic forces. This is the final issue of Logan’s Run Black Flower, the continuation of the iconic story started by science fiction masters William F. Nolan and George Clayton Johnson.