The episode was written Steve Gerber and Beth Woods and is the from the second season. In a way, this one reminds me of an original Star Trek episode titled "All Our Yesterday's" where Kirk and Spock meet the keeper of a library, named Mr. Atoz, (Mr. A to Z ?) who has recorded disks of their ancient history. Their world is on the verge of extinction because of a supernova and the planet's inhabitants enter a time portal to one of these previous civilizations to escape the destruction.
This episode has such a time portal via the Iconians. Their advanced but alien technology sends a probe to the Yamata and tries to merge with its technology and proves to be incompatible and causes a breach in the ship's plasma core and the ship explodes.
The Enterprise investigates while undergoing its own malfunctions brought about by the downloading of logs from the Yamato. One highlight of the episode is when Geordi takes the turbolift and goes for the ride of his life as it maneuvers at rapid speed back and forth, up and down, causing him to be thrust about the turbolift like a bouncy ball.
To complicate matters, the Romulans are interested in the Iconian planet and its technology and come head to head with the Enterprise, accusing the federation ship of violating the neutral zone. They too are having system failures because of the Iconian technology.
Picard leads an away team, consisting of Worf and Data, to the planet and its center of technology. The powersource opens up a gateway to other worlds, including the Enterprise bridge. The team decides to destroy the technology rather than let it get into Romulan hands to use it as a weapon. Worf takes Data through the porthole to the bridge after he becomes damaged by getting shocked by the powersource.
Data regains full functionality by using a self correction system. This gives Geordi the idea to perform a complete system shutdown of the ship. Picard ends up on the bridge of the Romulan via the porthole at the moment of the destruction of the Iconian technology center. The Enterprise beams him back as the Romulan ship is on the verge of self-destruction.