Star Trek's past and present collide when Captain Montgomery Scott's ship, the U.S.S. Jenolen, is discovered crashed on the surface of a self-contained solar system: a Dyson Sphere. This massive, artificially-constructed globe (roughly the size of Earth's orbit around the sun) contains aninverted M-Class biosphere built around a star. Responding to a mysterious signal, the U.S.S.Enterprise-D finds the lenolen where it impacted on the surface of the sphere nearly eight decades before. An away team finds the ship's life-support systems functioning, and a curiously jerry-rigged transporter system locked into a continuous diagnostic loop - with the pattern of at least one humanoid lifeform intact.

leutenant Commander Geordi LaForge downloads the recycling transporter pattern, and the legendary Captain Montgomery Scott materializes on the transporter pad exactly as he appeared seventy-five years before. As surprised as anyone to be standing in the 24th century, Scotty half-expects LaForge's Enterprise to be the one commanded by iames T. Kirk. A living anachronism, a depressed Scotty tries to find solace in a bottle of green alcohol and a holodeck recreation of the original Enterprise Bridge.

While the Enterprke-D continues to investigate the Dyson Sphere, Scotty tries to make himself useful by helping La Forge retrieve the information contained in the Jenolen's data banks. Upon discove'n~ng what appears to be an entrance to the sphere, the Enterprise is pulled in by an automated tractor beam and shut off from the outside universe. Inside, they find that solar flares have provoked a mass departure of the sphere's population and now, these same flares threaten to destroy the Enterprise.

Aboard the Jenolen, Scatty feels every bit a relic as his ship, but it is ultimately LaForge who convinces him that both ship and engineer are timeless classics. In a testimony to his reputation as a miracle worker, Scotty manages to re-start the Jenolen's engines and use the ship to pry the sphere's entrance open long enough to free the Enterprise. Captain Picard "loans" Scotty a shuttlecraft, and the renowned engineer embarks for parts unknown.