1) a boy went into hiding after he was lead to believe he killed his brother in a prank gone wrong. The boy ate a plant that contained toxic parasites and (for some inexplicable reason) the boy needs to be treated at a starbase hospital.
2) Data is responding to an internal homing device implanted by his creator Dr. Soong and creates a scenario that gets the crew off the bridge where he proceeds to take control of the ship and override commands from the captain in engineering.
3) Data's evil twin Lore is back, brought to the same location from Dr. Soong's homing device.
While the Enterprise crew works to get the ship's command controls back from Data's lockout sequence code, they know time is running out for the boy slowly dying from the parasitic toxins and must get him to the starbase treatment center within 36 hours.
Meanwhile, the Data and Lore reunion with their creator Dr. Soong isn't going that smoothly. They discuss Lore's past disturbing behaviors and why he had to be disassembled in the first place. Despite that, Soong is more trusting in Lore than he should be. He announces the reason he recalled Data to his work lab is because he had developed an emotion chip for him. He is also very old and sick and must rest before performing the implant procedure.
This gives Lore the opportunity to shut Data off and get the implant himself because, as he tells Soong, "you owe me, old man." He throws the tired old man across the room, gravely injuring him.
The Enterprise crew has figured out a way to beam to the planet and retrieve Data and get the lockout code. Soong refuses to go with them and he and Data are left to say good-bye in the short time they have left before the ship heads off to the treatment center.
Despite it's plot flaws, I enjoyed this episode and it was great having Lore appear again. Brent Spiner has a triple role here; as Data, the evil twin Lore, and the old Dr. Soong. The performances were so good that it was like watching three different actors.