While investigating a signal emitting from an ancient Promellian battle cruiser, Picard and an Away Team discover a ship that has been floating in space for over 1000 years. There are no survivors on the vessel, which has remained intact for centuries.
As the crew tries to determine what happened to the ill-fated cruiser, the Enterprise is plagued by a rapidly increasing energy drain which traps the ship in a holding pattern. Worse yet, the crew is simultaneously being bombarded by radiation and raising the protective shields only depletes more power.
Geordi, unable to determine the cause of the rapid energy loss, informs the Bridge that all of the ship's power will be depleted in three hours. And without energy for its shields, the entire crew of the U.S.S. Enterprise will be killed by the radiation.
In search of clues to help free the U.S.S. Enterprise, Riker and Data return to the ancient battle cruiser and begin reading over the ship's logs. Meanwhile, Geordi enlists the aid of Dr. Leah Brahms, a beautiful young engineering expert, to help him save the Enterprise from disaster.
The Promellian logs reveal that the ship was trapped by Aceton assimilators, devices which attract energy, modify it and convert it to radiation. During a centuries old battle between the Menthars and Promellians, the Menthars had used the assimilators to ensnare their enemy in the booby trap. The Promellians, in trying to escape, unknowingly supplied the power for their own destruction.
Meanwhile, Geordi tells Picard that their only hope for survival requires turning command of the starship over to the computer. But while running simulations of the maneuver, Geordi discovers that the radiation force striking the ship has reached fatal levels.
With time running out, Geordi abandons the idea of overpowering the booby trap. Instead, he gives the U.S.S. Enterprise all of the power it can muster in one quick blast and then immediately shuts down all non-essential power, allowing the ship to break the inertia and free itself from the trap.
Picard, taking control of the U.S.S. Enterprise, maneuvers it out of further danger by using the gravitational pull of an asteroid to slingshot his vessel out of the battle zone. To prevent other ships from suffering a similar fate, the U.S.S. Enterprise destroys the entire asteroid field and resumes its original course.