What? The vile Darkseid know Superman's secret identity? I don't believe it.
Yeah, it happened in this issue.
The story: in the streets of Metropolis Clark Kent is followed by Omega Beams (?) and escapes in the sewers. Then the rays hit him, and he arrives in Apokolips. The Hunger dogs steal his clothes, and he remains with only his costume. Darkseid has observed all these scenes alongside the Phantom Stranger (who already knew Superman's secret identity, see ACTION COMICS #585 for details).
Because you don't know this storyline, I'll tell you the rest of it: Superman fights in Apokolips against Darkseid's soldiers, but during the fight he falls into a flaming pit. With Darkseid laughing, the issue ends.
The story continue in ADVENTURES #427: Superman is still alive (the pits should destroy everything), but he has lost his memory. Amazing Grace finds him and uses her powers to suggest him to become the leader of the Hunger Dogs. Under his guide, they will be free, at last. Besides, Wolfman make us understand that Superman has his first sexual experience (with Amazing Grace; argh). During the battle against Darkseid's Parademons Superman turns against his fellows and joins with Darkseid. He was only pretending to save the Hunger dogs, and since the beginning he and Grace were Darkseid's allies. The conclusion is in AC #586: Orion and Lightray go in Apokolips to save Superman, and they do; using Mother Box, they restore Superman's memory and the Man of Steel goes to fight against Darkseid. The lord of Apokolips, beaten, sends him back on Earth.
Orion tells Lightray that he'll never reveal the truth to Superman: he is not a simple hero... He is a legend, and knowing what he has done in Apokolips would be too tragic to him.
This was a good story, but I never liked to know Superman having sex with a villain like Amazing Grace and he causing the death of hundreds, too.