The episode begins with the USS Enterprise approaching Mab-Bu VI, from where it has detected a distress call. Commander Data discovers that the distress call is standard for Daedalus-class starships, which went out of service 172 years ago. He then finds that the USS Essex, a Daedalus-class ship, was lost in the region 200 years ago. After concluding that assessing the situation from the ship is inadequate, Picard decides that an away team must visit the moon. Troi enters the stage, and indicates to Picard that she "feels" a living presence on the surface. Data announces that electromagnetic interference from electrical storms precludes the use of the transporter to the moon; Picard authorizes a shuttlecraft mission, manned by Riker, Data, and Troi.
As the shuttlecraft travels to the moon's surface the crew loses navigational control of the craft, and Data is forced to make an emergency landing. By the time the shuttle lands all communication with the Enterprise has been cut off by electromagnetic interference.
Riker suspects he has a broken arm due to the crash landing and the three crewmembers emerge from the shuttlecraft to learn about their surroundings. They observe the front of a massive electrical storm, and Riker comments that it appears nothing like the front of any other electrical storm he has seen before. A tricorder scan indicates EM bursts across the entire spectrum.
Back on the Enterprise the crew discuss possibilities for rescuing the crew of the shuttle. Ro Laren states she can use the descent angle of the shuttlecraft to approximate the landing site. Miles OâBrien enthusiastically proposes that he should transport to the surface and attempt to use a special device to allow a reliable transport of the away team. Geordi cautions Picard that OâBrien's chance of surviving the transport is about "fifty-fifty". OâBrien acknowledges the risk, and Picard grants permission.
OâBrien safely transports to Mab-Bu VI, and he is greeted with relief by Riker. As OâBrien prepares the transport procedure, one or more of the crew is struck by a large amount of what appears to be bolts of electricity. All but Riker are immediately incapacitated, and he hastens to begin the transport. Just before the four are transported, however, three light sources enter the bodies of Data, Troi, and OâBrien.
Upon their return to the Enterprise, Data, Troi, and OâBrien insist that the Enterprise conduct a survey of the polar region of the planet. The rest of the crew refuse, believing the idea to be absurd. The three then stage a violent uprising and take command of the ship. They use hostages as leverage to force Picard to change the course of the ship. Dr. Crusher determines that Riker was not affected because the pain from his broken arm somehow repelled whatever force possessed the others. Troi, the leader of the mutineers, then reveals that she is the captain of the Essex. She claims that their spirits were trapped in the electromagnetic fields of the planet, and if the Enterprise transports their bones back to Earth, they can be set free. However, Picard is skeptical of her claim because of their violent actions.
Dr. Crusher devises a way to free the mutineers' bodies from the possessive forces by inducing pain, but the plan fails because Data is unaffected. After Data threatens to kill everyone in the room, Picard weakly agrees to do whatever they say. The three try to return to the surface of the moon, but the problems that existed before still remain. However, OâBrien believes he can transport down as he did before, so the three take hostages and head for a cargo bay. Troi then reveals that the planet is a penal colony, and she hopes to use the bodies of the Enterprise crew to allow the other convicts trapped on the planet to escape. Picard says he would rather open the cargo bay doors and let them all die than risk the lives of his crew. At an impasse, the three spirits are forced to relinquish their hosts and return to the moon. Troi, Data and O'Brien are restored to normal.