Comic Title: Showcase #21
Publisher: DC (National Comics Publications, Inc.)
Address: 575 Lexington Avenue, New York, NY
Cover Date: Jul/Aug 1959
On Sale Date: May 26, 1959 Copyright Date May 26, 1959
Source: Library of Congress, Periodicals 1959

Newsstand Date May 26, 1959
Source: Newsdealer Magazine, V14 #3

Frequency: Bi-monthly
Cover Price: $0.10
Page Count: 32
Editor: Jack Schiff

Title: "The Secret of the Lost Continent"
Pages: 25

Feature(s):
Rip Hunter (of Earth-1)

Writer: Jack Miller
Penciller: Mike Sekowsky
Inker: Joe Giella

Reprinted In:
Showcase Presents:Showcase Vol. 1 TPB (2012)
Showcase Presents:Rip Hunter, Time Master Vol. 1 TPB (2012)

Feature Character(s)

• Rip Hunter (last appearance in Showcase #20; next appearance in Showcase #25)

Supporting Character(s)

• Jeff Smith (last appearance in Showcase #20; next appearance in Showcase #26)
• Bonnie Baxter (last appearance in Showcase #20; next appearance in Showcase #25)
• Corky Baxter (last appearance in Showcase #20; next appearance in Showcase #25)

Villain(s)

• King Darius and his army (no further appearances)
• A fleet of Cretans (no further appearances)
• D'Zar (tyrant leader of Atlantis; no further appearances)

Other Character(s)

• Alexander the Great and his army (no further appearances)
• Circe (next appearance in Action Comics #293)
• Circe's people (no further appearances)
• R'Del and her people (Atlanteans; no further appearances)

Comments:
Chap. 2: "The Forbidden Island"
Chap. 3: "The Doomed Continent"

Synopsis:
Rip Hunter and his team of time travellers journey to 325 B.C. to discover the secret behind a recently discovered stone tablet. The tablet supposedly reveals the location of Atlantis, but the writing has been worn away. When they reach 325 B.C., Rip's team meets Alexander the Great, who is in possesion of the tablet. The writing is legible, but it is missing a map.

Alexander tells Rip the tablet came from Aeaea, so Rip takes his team further in the past to locate the island from which it came. On the island of Aeaea, Rip meets Circe, whom is a supposed sorceress. Bonnie exposes Circe's magic as a fraud, then then find the tablet, complete with map.

Finally, Rip takes his team to the time and location given by the tablet, where they discover the lost continent. The island is inhabited by an advanced race from Jexjera. Rip helps them escape from the island, then watches the island sink into the ocean.