One of the Most Iconic Covers of the Silver Age
"The Hammer and the Holocaust!" takes place following Thor's battle with Hercules. The defeated Thor returns to Asgard to find all the rest of the Asgardians defeated by Seidring, who is in full possession of the Odinpower. After several pages of strange battle including Seidring hurling meteors at Thor, and trapping him in a bubble of liquid Wolfsbane (!?), Stan Lee comes up with a fairly innovative way for a half-depowered Thor to best a villain with the full power of Odin.
The subplot involves the god Pluto's plans to trap Hercules in Hades; and the backup story is a Tale of Asgard that briefly describes Ragnarok.
Overall we see that Lee and Kirby have really refined their formula, devoting roughly half the pages of the primary story to action - which plays to Kirby's strengths as an illustrator. This issue is also notable for having one of the iconic covers of the Silver Age Thor comics. There have been several homages to it since, most notably George Prerez' death of Supergirl cover for Crisis on Infinite Earths #7.