Comic Title: Superman #213
Publisher: DC (National Periodical Publications, Inc.)
Address: 575 Lexington Avenue, New York, NY
Cover Date: January 1969
On Sale Date: November 7, 1968 Newsstand Date November 7, 1968
Source: House Ad, Aquaman #43, Page 19

Newsstand Date November 7, 1968
Source: Comic Reader, #70

Newsstand Date November 7, 1968
Source: Newsdealer Magazine, V23 #9

Copyright Date November 7, 1968
Source: Library of Congress, Periodicals 1968

Frequency: Monthly, with the exception of March and September
Cover Price: $0.12
Page Count: 32
Editor: Mort Weisinger

Title: "The Most Dangerous Door in the World"
Pages: 15

Feature(s):
Superman (of Earth-1)

Writer: Cary Bates
Penciller: Curt Swan
Inker: Jack Abel

Reprinted In:
Best of DC #27 (1982)

Feature Character(s)

• Superman (last appearance in Action Comics #370; next appearance in Superman's Pal Jimmy Olsen #117)

Guest Star(s)

• Supergirl (last appearance in Adventure Comics #376; next appearance in Action Comics #371)
• Brainiac 5 (adult; disguised as Superman; last appearance in World's Finest Comics #168; no further appearances)

Supporting Character(s)

• Jimmy Olsen (last appearance in World's Finest Comics #181; next appearance in Superman's Pal Jimmy Olsen #117)
• Perry White (last appearance in World's Finest Comics #181; next appearance in Action Comics #375)

Villain(s)

• Lex Luthor (last appearance in World's Finest Comics #177; next appearance in World's Finest Comics #183)
• Mordru (behind-the-scenes as a voice; last appearance in Adventure Comics #370; next appearance in Superboy #173)

Guest Appearance(s)

• Adult Legion of Super-Heroes (behind-the-scenes; last appearance in World's Finest Comics #168; no further appearances)
• Element Man (behind-the-scenes; last appearance in World's Finest Comics #168; no further appearances)
• White Witch (behind-the-scenes; first adult appearance; no further appearances)
• Sun Man (behind-the-scenes; last appearance in Action Comics #289; no further appearances)

Comments:
Part II:"Success is a Heartbeat Away"

Synopsis:
Superman issues a statement to the public that a special vault with valuable contents will open when he dies. The vault is made of indestructible Supermanium and is kept under heavy guard. Luthor, provoked by articles in the Daily Planet, renews his efforts to kill the Man of Steel, who exhibits signs that he is weakened.

Luthor steals the vault uses a modified version of Brainiac's shrink ray. He then uses robots with Kryptonite inside to kill Superman. Thinking that he has finally succeeded in his goal, Luthor waits for the vault to open. When it doesn't, he uses every means necessary to break into the vault.

Luthor finally succeeds in opening the vault and discovers Superman inside. The Man of Steel apprehends Luthor, then explains that Mordru had magically imprisoned him in the vault. Supergirl and the adult Brainiac 5 then tricked Luthor into opening it by having the Legionnaire pose as the Man of Steel. Angry at being tricked, Luthor is nevertheless sent back to prison vowing vengeance.