The USS Enterprise receives a distress call from Dr. Clarke, the leader of a Federation scientific delegation on Ventax II, where the population is in a state of panic because they are convinced that their world will soon end. A thousand years ago, according to Ventaxian history, the population entered a Faustian deal with Ardra, their mythology's devil, in exchange for helping to clean and improve their heavily polluted planet. As the millennium is about to come to a close, the planet has recently begun experiencing earthquakes that were said to precede Ardra's arrival, fueling the fears of the Ventaxian people. As Captain Picard and Data discuss the matter with the Ventaxian leader, a sultry brunette appears in the chamber, announcing herself as Ardra. She proves her identity by seemingly starting an earthquake at will, and changing her form into that of both the Christian and then the Klingon devil. Ardra states that the thousand years are over and that she has come to claim the planet, including anything in orbitâthat is, including the Enterprise. When Picard and Data attempt to return to the Enterprise to contemplate this development, the Enterprise disappears before their eyes.
Picard, believing Ardra to be a fraud, calls for a Ventaxian arbitration hearing, which Ardra agrees to as long as Data acts as the arbitrator, due to his ability to be completely impartial despite his Starfleet position. Picard agrees to the choice of Data, knowing that he also cannot feel pressed by Ardra. The hearing reveals that Ardra never assisted the planet in cleaning up their pollution; the people improved their planet gradually after the deal was made. Despite his claims, Picard cannot convince the Ventaxian leader that Ardra is playing a con game. As the hearing continues, La Forge analyzes Ardra's power and discovers two cloaked ships in orbit: the Enterprise and another ship. La Forge relays this information to Picard, who, after a short recess, performs some of Ardra's "tricks" for the Ventaxian leader and for Data. Picard reveals that a team from the Enterprise was able to seize Ardra's cloaked ship, and used the technology aboard it to create the same effects. Picard further explains that "Ardra" and her co-conspirators were simply trying to take advantage of the Ventaxian mythology. With the hearing closed, "Ardra" attempts to simply abrogate the contract but finds herself detained for her fraud by the Ventaxian government.
The fact that the leader of the science team on the planet is named "Dr. Clarke" reinforces that this episode is a demonstration of Clarke's Law which states that "to the primitive mind, any sufficiently advanced technology is indistinguishable from magic."