When Jon Kent is kidnapped and Clark and Lois start to lose their memories of him, Superman must find out who's behind their memory loss! Dan Jurgens, Peter J. Tomasi and Patrick Gleason present the first monumental Superman crossover event following DC Rebirth that re-introduces Mr. Mxyzptlk! Collects ACTION COMICS #973-976 and SUPERMAN #18-19 in a hardcover format.