During an away mission to observe a pre-warp civilization, Commander Riker is injured and brought to a hospital, where the locals quickly realize he's not from their world. Despite the attempted intervention of the planet's sympathetic science minister, Picard and Troi's efforts to retrieve the first officer are stymied by the government's concern about the social crisis that a widespread revelation of Riker's presence could trigger.

The humanoid race of Malcor III is preparing to develop warp drive technology. Science Minister Mirasta Yale, lead researcher on their warp experiments, is suddenly visited by Picard and Deanna Troi. They calm her and explain that they come in peace. It is normal Federation policy to make first contact with a world when it reaches this level of technology. However, they have had to move ahead of schedule because Riker, disguised as a Malcorian, has gone missing. After touring the USS Enterprise, Mirasta agrees to help and arranges a private meeting with Chancellor Durken. After the meeting, Picard returns with Durken to the Enterprise and explains the benefits of a relationship with the Federation. Durken expresses some concerns, most notably with the Federation's unwillingness to share their technology, as well as how their arrival will change his society. Picard assures him that how contact proceeds will be up to him, and if asked to leave, the Federation will do so.

Meanwhile, Riker has been detained by security forces in a hospital, where he is barely conscious following an accident. Differences in Riker's physiology make the hospital administrator believe that he is an extraterrestrial. Riker is aided in his escape by a nurse who expresses her wish to "make love with an alien". Riker accepts her offer, but the escape attempt fails: he is spotted, and the guards catch and beat him, worsening his condition. Riker's presence at the hospital is reported to Security Minister Krola, who accuses Durken of hiding the truth about the "alien" presence. The Chancellor expresses his concerns to Picard about the Federation's covert intrusions, but accepts Picard's explanation of why the Federation does this. Krola, fearing a hostile invasion by the Federation, endangers Riker's health by reviving him prematurely so he may be interrogated. He tries to frame Riker as a murderer by shooting himself with Riker's phaser. Meanwhile, Durken is made aware that Riker is in danger of dying and tells Picard where he is. The Enterprise crew bring both Riker and Krola back to the ship. They are able to save Riker's life, and discover that his phaser was only set to stun, so Krola was in no real danger.

...
Wikipedia