In hyperspace, a probe is destroyed by passing fighters. Shortly thereafter, Capt. Lochley is awakened by a call from Lt. Corwin, telling her of the probe's destruction. "Is it them?" she asks, but the probe was destroyed too quickly to give much information. She gets up and goes to C&C.
When she gets there she informs the command crew that this is probably the scouting party they've been warned about. A large hostile force is looking for likely invasion prospects, and Lochley expects them to attack Babylon 5. She hopes to convince them that the station is more trouble than is worth, to save themselves from a difficult battle later on.
She orders that a lifepod be made ready for Sheridan and Delenn. Although Corwin assures her neither one will agree to leave the station, she vows to knock them unconscious herself if necessary to get them into the pod. Finally, she orders a stand-by Red Alert.
In Blue Sector, Bo and Mack, two maintenance workers, hear about the Alert as they finish working on the tubes behind a wall. Later, as Bo sweeps the floor with a piece of equipment and Mack works on a computer terminal, they overhear Lochley and Sheridan as they walk by arguing. Lochley wants Sheridan and Delenn in the lifepod, or at the very least to know where they are at all times. With all the White Stars away, this will give her one less thing to worry about, and allow her to do her job of protecting the station. At first Sheridan will have none of it, but finally agrees to do what he can after grudgingly admitting he would be doing the same thing in Lochley's position.
As they both leave on a lift, Mack and Bo comment on their approval of Sheridan's hands-on approach to everything. They like the fact that he is always down in the trenches, with everyone else. He is a good man, they both agree.
Later, their lunch is interrupted by a full blown Red Alert, as the scoutships activate the Jumpgate, and Mack and Bo are called for some service calls. Mack goes to C&C, and Bo goes to MedLab.
In MedLab, Franklin is organizing his team to deal with the wounded, and asks Bo to look at the console on the IsoLab. It is only giving them access to standard atmospheres, and he needs to be able to ask for anything on the fly, in case they need some strange atmosphere to treat the invaders. As Bo works on the console, he asks Franklin why he bothers getting ready to heal the invaders, rather than just letting them die. By way of explanation, Franklin relates that his father once got caught in the middle of a civil war of mid-range colonies. The Ares, on which he was XO, crashed, and two months later, when the Earth forces retook the base, his father and two other injured soldiers were found alive. The Doctor at the base had taken care of them despite the objections from his CO, because he believed life was sacred. It was then, Franklin says, that he decided to become a doctor, and it is why he will try to save anyone, regardless of sides.
"So... what happened to the doctor that helped your dad?" asks Bo. "Shot and killed by his own men," replies Franklin quietly. "They said he was a traitor." Bo then finishes the work on the IsoLab console.
In C&C, the secondary targetting console is on the blink, and Mack gets to work on it as the crew prepares for the three scoutships, which come in firing. Starfuries and the defense grid get two of the scouts, but in the meantime the aliens scan the station and try to access the codes for the defense grid. As the third scoutship is about to escape, Mack gets the secondaries back on line, which destroy the last alien ship. Lochley is relieved, and goes to talk to Garibaldi.
Mack joins Bo, who is now working on a deck in Blue Sector. Mack says he likes the new captain and is glad she's on their side. Bo replies that the rumors are she fought on the side of President Clark during the Civil War, but Mack dismisses his concerns. Many people were on the other side, he says, and one shouldn't listen to rumors anyway. As Bo finishes the work, they are called to fix a problem in Brown sector. They get in the lift, and are later joined by Lochley and Garibaldi.
Lochley and Garibaldi are arguing. Lochley is demanding to know why Garibaldi didn't tell her the aliens could download the tactical codes, but Garibaldi claims he is innocent. The Gaim didn't say anything, and he didn't think to ask. Lochley angrily tells him that it is his job to think of quesitons like that, and demands he go back to the Gaim and ask all the questions he didn't think of in the first place. With the assault fleet on its way, she wants a fighting chance of surviving the next 12 hours. Lochley and Garibaldi get off, and Mack and Bo go on their way.
After Mack and Bo finish fixing the problem in Brown sector, they are ordered to the Sanctuary to prepare it for a religious ceremony, as Lochley announces over the monitors that the first wing of the attack is coming through the jump gate.
From the sanctuary, Bo and Mack can see the firefight and explosions outside the station: a red explosion for human pilots blowing up, green for the invaders. Eventually, a lone White Star arrives and joins the fight, and Mack and Bo note a breaching pod closing in on the station. All personnel are ordered to the shelters. The station is being boarded.
Bo and Mack are on their way to the shelter, but the lift shorts out and stops. When they force the doors open, they find themselves in the middle of a firefight in Brown sector between the invading aliens and Zack's security forces. Zack orders them out and covers them, and they stumble into Byron's telepaths.
Byron assures them they are safe, and advises them to stay until the fight is done. Mack and Bo eventually figure out these people are the recently arrived telepaths, and when the fight dies down they get up to leave. Bo expresses his desire to be out in space fighting alongside the starfury pilots, and Byron uses his telepathic ability to make him believe he is, for a few seconds. Bo silently thanks him as they leave.
In the shelter, they overhear Londo and G'Kar. Londo is complaining about the situation, but G'Kar is quite calm. G'Kar practically grew up in shelters such as this, escaping from Centauri bombardment of the Narn cities, so he feels quite at home. Londo complains that the White Stars aren't there to protect them, and G'Kar reminds him they are coming back from guarding the Imphili homeworld ("The Paragon of Animals"). They both leave to "see how things are out there," as the second wave of invaders comes through.
One of the invading ships is damaged and crashes onto the station, making a sizeable hole in the hull. As maintenance bots put out the resulting fires on the outside, all maintenance personnel are called to Red One to deal with the fires on the deck burning through the hull.
As Mack and Bo are going there, they pass Sheridan and Delenn. Sheridan insists Delenn should get on the lifepod, but she refuses. Sheridan enlists Bo and Mack to escort her to the pod. "Look," says Sheridan to Delenn, "with luck the rest of the White Stars will get here on time and we won't even need the pods." "But what if we do?" asks Delenn. "What if the station falls?" "Then, as you said to me once," replies Sheridan, "I'll see you again in a place where no shadows fall" ("Confessions and Lamentations"). They kiss and Sheridan leaves Delenn in Mack and Bo's care.
Before they get to the pods, however, Delenn asks them their names. Delenn also asks what would happen to a lifepod if, shortly after launch, the equipment were accidentally smashed from the inside. Mack and Bo agree it would either crash on Epislon 3, or explode. Delenn then makes it plain that if she is put in a lifepod and forced to watch the station fall, her pod would suffer such an accident. "The President is right, ma'am," argues Bo. "It's not safe here for either one of you." "I know," replies Delenn. "But it is home for both of us." Mack and Bo let her depart, and she smiles at them before leaving.
The station shudders and Mack looks through a porthole and yells in triumph. "The cavalry is here!" he says. The White Stars have arrived at last.
With help from the White Stars, the fighting is soon over, and Mack and Bo get back to work. The shelter is a mess, and according to Bo there is a lot of work to do: a damaged hull to repair, garbage to be picked up, debris to be cleaned up from space surrounding the station, and airlocks to fix in Brown Level. "Typical," complains Mack. "They call all the shots, they get all the glory, we clean up the mess."
Then they see dozens of bodies lying still on the deck, draped in sheets. Dr. Franklin is going over them one by one, closing their eyes, making notes, and finally pulling the sheet over their heads. "Well," says Bo somberly, "maybe not all the mess."
As the cleanup continues, Mack and Bo are working on C&C and overhear Corwin reporting to Lochley that not a single alien made it back to report on Babylon 5. Lochley is pleased, and does not expect them to try again.
"Captain, ehr... Captain Lochley!" yells Mack suddenly. The Command Deck falls into an expecting silence, as Mack continues lamely. "Well, Captain, ah, I know you're new here and all and, ah, I just wanted to say, you're okay in my book, ma'am." "Thank you," says Lochley sincerely, smiling widely. Mack goes back to work.
Later that day, Mack and Bo are on their way to lunch when they pass Sheridan and Delenn, walking hand in hand, in a corridor. "Hello Mack, Bo," she greets them by name as they walk by.
"Bo?" "Yeah?" "She remembered my name." "Our names." "I think I'm in love..." "She's married!" "We'll work something out."