Comic Title: Sea Devils #21
Publisher: DC (National Periodical Publications, Inc.)
Address: 575 Lexington Avenue, New York, NY
Cover Date: Jan/Feb 1965
On Sale Date: November 19, 1964 Newsstand Date November 19, 1964
Source: House Ad, Brave and the Bold #57, Page 30

Copyright Date November 19, 1964
Source: Library of Congress, Periodicals 1964

Frequency: Bi-monthly
Cover Price: $0.12
Page Count: 32
Editor: George Kashdan

Title: "The Forty-Fathom Doom"
Pages: 25

Feature(s):
Sea Devils (of Earth-1)

Penciller: Howard Purcell
Inker: Sheldon Moldoff

Feature Character(s)

• Sea Devils (last appearance in Sea Devils #20; next appearance in Sea Devils #22)
• Dane Dorrance (last appearance in Sea Devils #20; next appearance in Sea Devils #22)
• Biff Bailey (last appearance in Sea Devils #20; next appearance in Sea Devils #22)
• Judy Walton (last appearance in Sea Devils #20; next appearance in Sea Devils #22)
• Nicky Walton (last appearance in Sea Devils #20; next appearance in Sea Devils #22)

Villain(s)

• Dr. Quad (an evil scientist; no further appearances)

Comments:
Chap. 2: "The Octopus with the Human Brain"
Chap. 3: "Dr. Quad's Secret Weapon"

Synopsis:
The Sea Devils are sent in search of a wrecked ammunition ship. They discover a false bottom on the ocean floor. The ship has sunk through the layer of film. When the divers find the ship, Biff tries to kill them twice. Dane then finds a cave where the real Biff is held captive. Biff's captor is Dr. Quad, a scientist with amazing transformation abilities.

Dr. Quad was disguised as Biff. He attempted to kill the Sea Devils to protect the secret location of his laboratory. He tries killing them again, so he can finish building a moly ray which can transform sea water into anything he desires. The Sea Devils escape Quad's trap, then battle the creations of the moly ray. Quad changes himself into a duplicate of Dane, but Dane proves to the others that he is their real teammate. Dr. Quad is defeated, and the moly ray is destroyed.