Superman returned in 1950 in a follow-up 15 part serial where he faced off against Atom Man who was none other than (spoiler alert) Lex Luthor.
The story contained a couple interesting ideas that were recycled in later Superman tales. For one, Luthor fabricated his own Kryptonite, a plot point used with varying success in Superman III. Also, Superman was sent to a realm called the empty doom which was essentially a proto Phantom Zone. You know I kinda like that name, The Empty Doom!
Check back next week for another chapter in The Super History of Superman.