Mera and Aquaman are honored in Atlantis with a new statue. Aqualad is given a new sea mount, Sea Imp. But while they party, a group of Atlantean farmers is attacked by a two-headed monster, who captures one citizen and his mount. When Aquaman hears the news, he and Aqualad go to rescue the citizen.
They approach the cave of the monster, and Aquaman distracts the beast while Aqualad rescues the farmer. But the monster spots the escaping Aqualad and goes after him, panicking Aqualad's new mount. Aquaman again distracts the beast, which knocks him senseless. Aqualad rushes to his rescue, only to discover that the beast has vanished.
Approaching from the deeper water, a familiar (to Aquaman) form approaches. It is Aquaman's old friend Kaltor, the first Atlantean he ever met, who taught him how to swim in the deep, and trained him in how to avoid the dangers of the oceans. He tells Aquaman that he's trying to destroy the monster, and makes Aquaman swear to help him destroy it.
They return to Atlantis so Aquaman can take the oath, when they are captured by Lukhan, a banished Atlantean criminal.
Kaltor has no patience with the bandit, and knocks him out. They wonder why Kaltor needs Aquaman's help. In Atlantis, they find that Kaltor's daughter, Starene, has followed him to the city to try to get him to give up pursuing the creature.
When the expedition leaves, Starene goes with it. A jealous Mera follows. The expedition splits, with Kaltor going alone, and Aquaman, Aqualad and Starene in another direction. Kaltor says he'll blow on a conch shell if he needs help.
Mera is captured by the creature, who takes her into caves and deposits her next to a conch shell. She blows on it, hoping someone will help.
Hearing the sound of the shell, Aquaman and company rushes to help. The spot the monster burying Mera's chariot, and chase it. Aqualad manages to get a stalactite aimed at it for the kill, but Aquaman deflects the blow and has Aqualad lasso the creature. The follow it, and watch in wonder as it transforms into Kaltor.
Kaltor explains that he tricked Aquaman into making the oath so he will kill the creature that Kaltor becomes. After rescuing some trapped Atlanteans from a mine, Kaltor was exposed to a gas that turns him into the beast. He thinks the next change will be permanent. And Aquaman has to kill the beast if he ever wants to see Mera again.
Aquaman agrees that he has to kill the beast, even as Kaltor transforms again and attacks the group. Aqualad rescues Starene, and the trio go after the beast by sending in eels as scouts. The eels find Mera, and the beast finds them shortly after.
Aquaman uses a sword in the beast's loot to attack, and Aqualad is captured by the beast. Aquaman's sword breaks and he uses Mera's wedding ring to cut another out of shell.
He kills the beast, which transforms back into a living Kaltor once dead.
The cover has a serious dilemma: Aquaman has to chose between a beast that once saved his life and Mera and Aqualad...
What happened to Mera's oath last issue that she intended to follow Aquaman on his next mission? Never mind, she follows anyway...
Aqualad's Sea Imp isn't well trained, and he has to learn how to control it as he goes.
Kaltor presumably found young Aquaman when he was just starting to learn about his powers, and saves his life several times. This fits with Aquaman's pre-Crisis origin as the son of a lighthouse-keeper who trained him to use his powers for good.
Shorts and notable ads in this issue: a one-page public service cartoon about the UN, a half-page "Chief Hot Foot" cartoon, a one-page text piece entitled "They're Real, Live Fish".
There is a circulation statement in this issue. Here are the numbers: The first column is the average over the preceding twelve months, the second is the exact numbers for the issue nearest their filing date (October 1st, 1964). The total number of copies printed: aver=337,000 and exact=350,000. The total subcribers: aver=578 and exact=795, and through dealers: aver=226,000 and exact=239,000. Free copies sent out for both columns was 387, which made the total number of copies distributed: aver=226,965 and exact=240,182. Compare these numbers to today's sales numbers for a bit of a shock.
Good tale with interesting implications.