Comic Title: Action Comics #312
Publisher: DC (National Periodical Publications, Inc.)
Address: 575 Lexington Avenue, New York, NY
Cover Date: May 1964
On Sale Date: March 26, 1964 Newsstand Date March 26, 1964
Source: House Ad, Superman's Girl Friend Lois Lane #49, Page 30

Copyright Date March 26, 1964
Source: Library of Congress, Periodicals 1964

Frequency: Monthly
Cover Price: $0.12
Page Count: 32
Editor: Mort Weisinger

Title: "The Fantastic Menace of the 'LL's'"
Pages: 12

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

Writer: Leo Dorfman
Artist: Jim Mooney

Reprinted In:
Showcase Presents Supergirl Vol. 2 TPB (2009)
Supergirl:The Silver Age Omnibus Vol. 2 HC (2018)

Feature Character(s)

• Supergirl (last appearance in Action Comics #311; next appearance in Action Comics #313)

Supporting Character(s)

• Comet (last appearance in Action Comics #311; next appearance in Action Comics #314)
• Lori Lemaris (last appearance in Action Comics #312; next appearance in Action Comics #313)

Villain(s)

• Lady-Killer Kane and his gang (Stebbins named; no further appearances)

Other Character(s)

• A movie producer and crew, an F.B.I. agent, "Madcap" Marilyn Drake, and students of a space college (no further appearances)

Synopsis:
Supergirl receives a predictor machine from the Cybernians. The machine predicts that the letters "LL" will have a profound influence on Supergirl's day. The predictions turn out to be corrects as several key events are linked to words containing those letters. Supergirl helps a movie studio shoot a movie, helps capture Lady-Killer Kane, then tests a new space ship.

While testing the ship, Supergirl is endangered by a swarm of Kryptonite meteors. Comet has been changed into Biron by Halley's Comet. In his human guise, Biron pilots the ship to safety. Supergirl is unaware that Comet was responsible for her rescue.