Captain Atom 37 (Jan 90) brings back a pre-Crisis Superman villain, the Atomic Skull, in a story by Bates, Weisman, Kayanan, and Tanghal.
After an opening that sees Nathaniel Adam attend the funeral of one of the Captain Atom team, but not an important figure, he calls on Chester King, the arsonist who turned over a new leaf. The guy now lives in Las Vegas, and Adam asks him to look after the Silver Shield. That seems a bit much to ask of someone one barely knows, but Chester agrees. Then the Martian Manhunter telepathically contacts Adam, letting him know about a radiation leak at a nuclear power plant.
Captain Atom heads to the plant, only to find the leak is being caused by the Atomic Skull. He has come to steal some radium, which he needs to maintain his powers. This is the Albert Michaels Atomic Skull, last seen in Teen Titans Spotlight, even though he looks quite different. The two men fight, and Atomic Skull blasts Captain Atom.
Atom thinks he has been knocked out by Skull, but in fact he was shunted ahead almost 24 hours. It takes Nathaniel Adam a while to figure this out, and he can't understand why Oberon is angry with him, or why Jeff doesn't show up for a planned meeting.
But once he realizes the situation, he knows that the Atomic Skull will once again be going after radium, and heads out to face the guy again. This time he gets the jump on the villain, stealing his stolen radium, and then taking him down. A new Atomic Skull would debut in the pages of Superman a couple of years down the road.
He also manages to meet up with Jeff, and only then learns that Peggy has broken off the engagement and taken off. You'd think he would have found out about that somehow.
The issue closes on Chester King, who is a bit freaked out by the Silver Shield.