Schubert threatens to cause worldwide flooding by using powerful microwaves to melt Earth's polar ice caps, unless th...

When a multimillion-dollar underwater probe malfunctions and begins attacking any ship that travels near it, Mark mus...

Mark, investigating a power outage, discovers a centuries-old hawk statue from the legendary civilization of Mu. The ...

The oceans are leaking through a fissure in the ocean floor. A con-man named Muldoon agrees to guide Mark through the...

Using his genetic scientists, Schubert produces a giant jellyfish which he intends to release unless his extortion de...

Mark is somehow linked with a man named Billy, existing in a wild west town, who appears to be his twin. Investigatin...

Schubert attempts to make a satellite weapon to knock out Earth's communications. However, to power the weapon, he ne...

An underwater landslide transports Mark to Verona, Italy...in the days of Romeo and Juliet.

C. W. develops a Jekyll-and-Hyde personality after swallowing a mysterious liquid.

Mark re-encounters Muldoon, his nemesis from "Giant," who is using a sea monster to make island natives sacrifice you...

An impish little man enters an underwater station and causes the crew to become irrational simply by touching them. A...

While investigating the mysterious loss of three ships in one part of the ocean, Mark and the crew of the Cetacean en...

Mark goes undercover to investigate members of a carnival planning to break into a museum. The only way to break into...