The series is divided into six sections in the table of contents, sections which are mostly bound together by theme. Part of the problem of this book - something which becomes evident the more you read - is that these stories were not originally conceived as sharing a continuity with each other. It's something the fanboys and the editors threw together after the fact, out of a strange desire to link DC's future timelines together. We open with "Pre-Disaster Warnings" opens the book with a few time travel stories set in then-contemporary times. The first is a three-parter about a man from the post-apocalyptic future journeying to present times and telling people about the world to come. After that, the section contains a Superman story in which Superman is manipulated into creating a divergence in his timeline's future so that the Legion of Super-Heroes continuity and Great Disaster continuity exist in separate timelines. It's the kind of fanboy continuity obsession I understand all too well, given my own history with the Official Handbook of the Marvel Universe. Someone thought it was important to explain how DC could have two very different futures - ignoring the fact that truly neither of them will ever become the DC Universe's present. The inclusion of this Superman story seems very ill-judged to me as it's deeply entwined with Jack Kirby's Kamandi #29, a story which revealed what had become of Superman's indestructible costume in that future world. Continuity mavens claim Kamandi and OMAC's futures belong to the same timeline as the other stories reprinted here, but, notably, this is not a Kamandi or OMAC collection. The book would be improved if this Superman story were eliminated and it published in a Kamandi volume instead, it's strictly for the continuity dorks (no offense, fellow dorks).
The "Day After Doomsday" section features a series of short (1-2 page) stories which appeared in odd ducks like Weird War Tales through the 70s and early 80s, but are not presented in print order because... I think some continuity nerd figured out a chronological sequence for them? Anyway, these were conceived of by Len Wein and are essentially cruel tales about the post-apocalyptic world, often riffing on abused tropes from the sub-genre. For instance, the last man on Earth is named Adam; he meets the last woman who is named... Gertrude. In another, a man finds a vending machine but he has no dimes - what a tragic twist! - but then he breaks it opens and finds - nothing but dimes! - what a doubly tragic twist! Steve Ditko drew a few of these, including one where a man is killed by radioactive hippies. I'm making that one sound more entertaining than it is. Anyway, there's also some very early Frank Miller and overall, you do get a few good dark chuckles out of this series.
The "Tales of the Atomic Knights" section is the main event, the John Broome/Murphy Anderson Atomic Knights adventures which appeared in Strange Adventures from time-to-time in 1960-1964. The series is set in 1992, following an atomic war in 1986 which has decimated humanity and destroyed most crops and animals around the world. The lead character is a former soldier, Gardner Grayle; he teams up with teacher Douglas Herald, Herald's sister Marene, twin brothers Hollis & Wayne Hobard and scientist Bryndon Smith. Discovering a set of armours which have developed tremendous resistance to radiation, the six put on the armours to defend a town of survivors from the people preying upon them, then set out to explore the worldwide devastation, battling giant monsters, mole men and Atlanteans (Atlanteans are the recurring enemies, believe it or not). Along the way they find a pair of dalmations which have been mutated to a tremendous six and they become the heroes' steeds (with a litter of pups promising more giant dogs to come). The stories are fairly typical of DC's adventure hero team books and, settting aside, are much like Challengers of the Unknown. The best thing about the series is Anderson's luscious artwork; he made the post-apocalyptic world look like a storybook.
The "Gods Return" section has a few problems. It opens with Jack Kirby's Atlas story from First Issue Special #1. I don't know who decided this was a post-apocalyptic tale, because it strikes me as a story set in the distant past as it is basically Kirby doing a Conan adventure. It never connects to the continuity of the other tales in this book and ends on a cliffhanger to boot; I love Kirby, but it doesn't really belong here. The remainder of the section is devoted to the 12-issue run of Hercules Unbound from 1975-1977. It opens with World War III causing Hercules to be set free from an island where'd been chained up for several thousand years. Hercules ventures into a world of mutants and battles Ares, who lords over the mayhem. The first six issues are by Gerry Conway and Jose Luis Garcia-Lopez and it's a decent enough series (though the World War III timeline in Hercules doesn't actually fit the Atomic Knights', despite what continuity nerds have established).
Conway & Garcia-Lopez left after #6 and in came David Michelinie as writer for #7-9, then Cary Bates for #10-12 with Walter Simsonson on art for the remainder. Initially, Simonson was inked by Wally Wood who seriously overpowered Simonson's pencils. It's notable particularly in Wood's ever cleavage-happy females, who don't look remotely like Simonson's women. Layton inked one issue but finally Simonson took over full art for the last two issues and they look pretty much as you'd expect; it's big, glorious Simonson art with gods at war. These latter issues are also where the continuity tie-ins come in - issue #10 guest stars the Atomic Knights (providing the cover for this Showcase collection) and picks up a dangling contintuity matter from OMAC.
The "More Tales of the Post-Apocalyptic World" section has a bunch of man-animals back-up strips from Kamandi - no idea why they're here when Kamandi is otherwise absent. There's also a stray "Day After Doomsday" tale.
Finally, the "Alternate Endings" section. This opens with a Superman/Atomic Knights team-up story from a 1983 issue of DC Comics Presents. Like the earlier Superman story, it's a bit problematic. In this, Superman meets the Gardner Grayle of his own reality, who turns out to be a soldier in a virtual reality machine. The story claims that all of the Atomic Knights stories (and Hercules Unbound) were merely delusions of Gardner's atomic war-obsessed brain. Superman enters this virtual reality and makes various cutting remarks at how unbelieveable the Atomic Knights' world is (as if believability ever stood for anything in the DC Universe; your rogue's gallery includes a giant ape with Kryptonite eyebeams, Supes!). Heck, part of Superman's case against the Atomic Knights is that their Hercules has the wrong hair colour (horrors! I hope someone was arrested over it!). The story is, ultimately, an attempted deconstruction of the Atomic Knights. In the climax, Gardner sums up what appears to be the authors' view of the Atomic Knights:
"This whole project was misguided from the start -- trying to figure out how to live in a post-holocaust world... how to keep making war in it! To believe that civilization can continue in the face of that cataclysm is a fantasy... a fantasy as monumentally false as the one you helped me to give up here today! The task before mankind isn't to survive an atomic war! It's to work in this world we're living in to make certain such a war can never begin!"
Yeah! In your face, speculative fiction authors! Hang your heads, Broome & Anderson! You have been scorched by the creators of Blue Devil! Of course, the weird thing is that Kamandi still existed in the DC Universe after this story. And OMAC. More amusingly, the true holocaust of 1986 at DC Comics would be the event Crisis on Infinite Earths, another attempt by DC continuity geeks to force the entirety of DC Comics to "make sense," but instead created problems which persist to this day. Forget about learning how to stop atomic war - DC needed to learn how to survive publishing ennui.
The book concludes with a text piece written by continuity chairman Paul Levitz for the Amazing World of DC Comics at a time when Hercules Unbound was still being published. In it, Levitz tries to make sense of the "Great Disaster" continuity, using various notes from Kirby and Conway about where their series fit in, but it includes details which never made it to the comics (Levitz claims World War III in Hercules Unbound was started by Darkseid; Cary Bates would later make it the "anti-gods").
As a whole, this is a decent enough collection; the Atomic Knights were fun and Hercules Unbound is interesting, especially when Simonson enters. "The Day After Doomsday" stories were good - but the other continuity detritus surrounding this book would've been better excised. There is ultimately something very sad about reading pre-Crisis stories which were so, so obsessed with continuity matters which Crisis would ultimately render moot. To this day, DC seems determined to seek out stories which have their own continuity or personality and stamp it out until those stories conform to the line-wide narrative.