"It's a mystery in space: Why would the Guardians of the Universe hide top-secret intel deep in the bowels of a secret vault on Thanagar Prime? The answers will change the DC Universe forever! The events of the Dark Nights: Metal and Justice League: No Justice have transformed the DC Universe in ways both wonderful and terrifying. Martian Manhunter, John Stewart and Hawkgirl avoided 'Drowned Earth' with a detour to Thanagar-Prime: J'onn looks to tap into the ancient Martian mental database, Green Lantern struggles while practicing his new UV powers, and Kendra searches for answers about her connection to the Totality."-- Provided by publisher.