Comic Title: Action Comics #240
Publisher: DC (National Comics Publications, Inc.)
Address: 480 Lexington Avenue, New York, NY
Cover Date: May 1958
On Sale Date: March 27, 1958 Copyright Date March 27, 1958
Source: Library of Congress, Periodicals 1958

Frequency: Monthly
Cover Price: $0.10
Page Count: 32
Editor: Mort Weisinger

Title: "Secret of the Superman Sphinx"
Pages: 12

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

Writer: Otto Binder
Penciller: Wayne Boring
Inker: Stan Kaye

Feature Character(s)

• Superman (last appearance in World's Finest Comics #94; next appearance in Superman's Pal, Jimmy Olsen #29)

Supporting Character(s)

• Lois Lane (last appearance in Superman #121; next appearance in Superman's Pal, Jimmy Olsen #29)
• Perry White (last appearance in Superman #121; next appearance in Superman's Pal, Jimmy Olsen #29)

Other Character(s)

• The President (no further appearances)

Synopsis:
Lois Lane discovers a Clark Kent robot in the Daily Planet supply room. She suspects Superman uses it when he is busy. She breaks the robot in order to trick the Man of Steel into revealing his secret identity.

Meanwhile, Superman is alerted to a strange satellite orbiting the Earth. He flies to engage it and discovers it is a sphinx with a face resembling his own. The sphinx sends deadly heat rays from its eyes toward the Earth and keeps Superman away with Kryptonite beams.

Superman eventually finds a way to get close to the sphinx by shooting himself into space aboard a lead satellite. Clark shows up at the office at the same time proving Lois’s suspicions wrong. However, unknown to Lois, the Superman in space is merely a robot. Superman himself created the sphinx to test a new military weapon in secret. The mystery goes unsolved by everyone except Superman and the government.