At the start of the episode, Kurn and Worf's ship is under attack by a Klingon-Duras ship. Three of the bridge crew are dead: one has a shard of metal embedded in his face, another dead crewman is being dragged off-deck by another officer, and a third one dies when his console explodes.
Kurn orders Worf to take the ship into the corona of a nearby star. As the ship nears to photosphere, it jumps into warp and causes an eruption on the surface that destroys two pursuing Birds-of-Prey.
In the High Council chambers, a Klingon soldier challenges Gowron. Worf steps in to defend the Chancellor and stabs the attacker.
A Bajoran ship attacks a Federation colony on Solarion IV, killing many civilians. It is later revealed that the Cardassians staged the attack in order to manipulate Starfleet into solving their own problems with the Bajorans.
Ensign Ro explains the reasons behind her court martial. She disobeyed orders during an away mission to Garon II and her recklessness resulted in eight officers being killed.
The Crystalline Entity - an alien force first encountered by the Enterprise in the 1st season episode "Datalore" - attacks a human outpost on Melona IV. It begins systematically consuming all organic life on the planet. As Riker, Data and Dr. Crusher move the settlers to safety inside a cave, a woman named Carmen (portrayed by Susan Diol) goes back to help an elderly man who has fallen. Both of them are caught in the path of the Crystalline Entity's absorption beam and obliterated. The rest of the colonists survive.
The Crystalline Entity later attacks the Kallisko, a Borealian transport ship, and consumes its entire crew.
At the start of the episode, the Enterprise runs afoul of a quantum filament which disables the ship. Another filament strikes soon after the first and the conn and ops stations on the bridge explode. Lt. Monroe, a red-shirted officer, is killed in the explosion.
Monroe is the only confirmed death in the episode, but in all likelihood there would have been other fatalities.
An alien ship smuggling weapons arrives at a Zakdorn supply depot. The vessel engages the Enterprise-D in battle and the Enterprise returns fire, striking the alien ship's phaser banks. Although the blast was only intended to disable the ship, the amount of munitions aboard react violently and detonate, destroying the ship.
A Romulan invasion force travels to Vulcan aboard three stolen Vulcan ships. Spock exposes the Romulan threat and the Enterprise is alerted, ready to stop the invasion. However, a cloaked Romulan warbird appears beside the Vulcan ships and destroys them, killing 2000 Romulan troops rather than let Starfleet take them prisoner.
The Enterprise-D is destroyed with all hands When they attempt to rescue the USS Bozeman from a temporal anomaly. However, the ship is caught in a causality loop where the event continues to repeat itself. With each repeat, members of the crew become more aware of the loop until they manage to save themselves and the Bozeman, escaping the causality cycle with no loss of life.
A "forty-niner" (portrayed by Jack Murdock) is pleading for hand-outs in 19th-century San Francisco. He is approached by an alien disguised as a human that steals his neural energy, leaving his gray, lifeless body slumped in the street.