Captain Sheridan (Bruce Boxleitner), finished with a long session with the Non-aligned Worlds, is at batting practice on the station’s baseball field. Chief Garibaldi (Jerry Doyle), joining him, mentions strange energy readings in Grey Sector. Sheridan decides to investigate. Londo Mollari (Peter Jurasik) and Vir (Stephen Furst) are singing opera in the corridor, when a strange, hooded figure grabs the Ambassador from behind. Londo realizes with pleasure that it is Vocator Urza Jaddo (Carmen Argenziano) an old friend who is a war-hero back on Centauri Prime and a member, with Londo, of the duelling society called Coro Prido or Proud Knives.

Sheridan walks into Grey 10 and pokes around a bit. He finds a Markab corpse with its head bashed in. He tries to notify Garibaldi, but his link does not function, the corpse grabs Sheridan’s face, and a white glow passes into him. Later, in Medlab, as he is examined by Doctor Franklin (Richard Biggs), his vision turns white. He decides to rest for a while.

As Londo prepares dinner for his friend, he tells Vir about his childhood, when House Mollari and House Jaddo were close. He was never able to beat Urza at fencing. Sheridan can’t sleep. He hears noises and sees an alien creature hovering over his bed. He takes out his PPG and fires, but his shots pass through the creature. Security arrives in response to the gunfire, but cannot find the creature, which Sheridan knows is a Grylor. Garibaldi reports that the Markab committed suicide by bashing in his head.

Londo and Urza continue drinking. When Urza mentions his wife Marilya, Londo sadly remembers his lost love Adira Tyree. Urza reveals that he knows the Narn did not start the war with the Centauri but were forced into it by the faction that assassinated Prime Minister Malachi and helped raise the Emperor Cartagia to the throne. Urza’s house is being accused of treason and he is seeking Londo’s support. Londo pledges his aid. In C&C, Sheridan’s vision goes white again and he sees the Icarus exploding, killing his wife.

Londo contacts Lord Refa (William Forward), who says Urza is a traitor and supporting him would be dangerous. Back in batting practice, Garibaldi tells Sheridan that the dead Markab passed through Sector 14 on the way to Babylon Five. Garibaldi explains that Sector 14 is off limits because of the sudden reappearance of Babylon Four there last year. He offers a copy of the records.

Urza’s banquet turns sour when Urza announces the resolution against him and House Jaddo will likely pass. Lord Refa is the one responsible. Like the late Emperor Turhan, he is disillusioned and suddenly challenges Londo to the Morago Duel to the Death. Londo accepts. Studying Garibaldi’s footage, Sheridan sees his parents and then they disappear. He leaves his quarters. Ivanova (Claudia Christian) and Garibaldi both learn that Sheridan is missing. Delta 1 launches with Sheridan inside. Londo prepares to duel with his friend.

Garibaldi takes off after Sheridan in Delta 2. Mollari is cut on the arm—first blood. A time portal opens up in Sector 14 and with a scream, the white energy pours out of Sheridan and through the portal. Garibaldi grapples Sheridan’s ship and brings it back before it too can be pulled into the portal. Urza, as he is winning the duel, leaves himself open to attack and Londo stabs him. Dying, Urza explains that he did this to spare his family his disgrace.

Sheridan explains that the Markab was carrying an alien being that wandered in from Sector 14. It jumped into Sheridan and through images of fear, loss, and home asked Sheridan to return it. Londo is drinking to Urza. He explains to Vir that he is now responsible for Urza’s family. They are now House Mollari and immune to Lord Refa’s resolution.

The opera tunes sung by Londo and Vir were written by Christopher Franke, composer of the Babylon Five theme. This was the last episode to be written by someone other than J. Michael Straczynski until one in Season Five. If something about Sheridan’s vision of the Icarus seems off, it’s because this episode was supposed to air before the explanation of the tragedy in the episode In the Shadow of Z’ha’dum. Knives was delayed because of the complex special effects. The Centauri rule that Londo must inherit Urza’s house seems to be based on a similar law in Frank Herbert’s Dune. The section in Grey Sector that Sheridan goes to is called the Babylon Five Triangle, and this is neither the first nor the last spooky thing to happen there.