INT. MED-LAB: One of the acid holes from the colonists' siege has yielded access to sub-floor conduits. Vasquez cuts an opening into one of the main shafts. Bishop looks into the shaft with a flashlight, nothing. He hands the flashlight back to Vasquez and then sits on the edge of the hole.

RIPLEY: How long?

BISHOP: This duct runs almost to the up-link assembly. One hundred eighty meters.

Ripley passes him a portable terminal and a small satchel containing tools, which he pushes into the constricted shaft.

BISHOP: Say, forty minutes to crawl down there.

RIPLEY: Right.

BISHOP: An hour to patch in and align the antenna. Thirty minutes to prep the ship, and about fifty minutes flight time.

Bishop lies down in the shaft, on his back. Vasquez hands him the flashlight.

RIPLEY: It's going to be close.

Vasquez pulls out her service pistol and hands it to Bishop. He looks it over and gives it to Ripley.

RIPLEY: Good luck.

BISHOP (cheerfully): See you soon. Watch your fingers.

Vasquez and Ripley place the metal plate over the hole again. Bishop turns over and squirms into the shaft, pushing the equipment along ahead of him with a scraping rhythm. Vasquez begins spot-welding the plate in place behind him.

VASQUEZ: Vaya con dios, man.

INT. CONDUIT: Bishop moves on, crawling in a rhythm with his body and breathing. Ahead of him, the conduit dwindles straight to seeming infinity, ending in a tiny white dot.

INT. CORRIDOR: Sentry units 'C' and 'D' are blaring away as the alien onslaught try again from another approach. Their numbers decreasing as they contact the guns.

INT. OPERATIONS - TACTICAL: Ripley and Vasquez run to the tactical console, where Hicks is mesmerized by the images from the surveillance cameras.

The flashes of the sentry-guns flare-out the sensitive video, but impressions of figures moving in the smoky corridor are occasionally visible. The robot- sentries hammer away, driving streamers of tracer fire into the swirling mist.

HICKS: This is unbelievable. Forty meters and closing. Fifteen.

RIPLEY: How many?

HICKS: I can't tell. Lots. D-guns down fifty percent.

INT. CORRIDOR: The guns' fire lash out at the invaders. High-pitch screams of dying creatures echo all around the corridor.

INT. OPERATIONS - TACTICAL

HICKS: C-guns right behind it.

The monitors show the war. There is an occasional visible glimpse of one of the creatures, but it is quickly dispatched by the spray of bullets, throwing acid blood all over the corridor.

HUDSON: They ain't stoppin' 'em. They ain't stoppin' 'em.

HICKS: Hundred-fifty rounds on D.

HUDSON: Come on. Come on, baby. Come on, D!

CLOSE-UP ON SENTRY DISPLAY: showing 91 rounds in D-gun and dropping. The monitors show more scenes of the seemingly-endless battle going on.

Lots of creatures exploding upon contact with bullets, acid thrown everywhere.

HUDSON: Come on! Come on!

CLOSE-UP ON DISPLAY: The word CRITICAL starts flashing and beeping on the screen, indicating the gun is almost dry.

HICKS: D-guns down to twenty. Ten.

D-gun goes empty.

HICKS: Damnit!

Hicks gets up quickly, grabbing his gun, and starts to head toward the battle-raged corridor.

INT. CORRIDOR: D-gun clicks empty and continues tracking. Then the firing from the remaining gun stops abruptly. Both guns' sit smoking, still swiveling to locate any possible targets.

INT. OPERATIONS - TACTICAL: Ripley is watching the monitors very closely. The video image is a swirling wall of smoke. There are black and twisted shapes scattered at the edge of visibility. However, nothing emerges from the wall of smoke.

RIPLEY: Wait! They're retreating. The guns' stopped them.

Hicks freezes where he is and stares at the monitors in disbelief. Nothing comes through the smoke and blackness.

HICKS: You’re right.

The moment stretches. Everyone exhales slowly.

HICKS: Next time, they walk right up and knock.

The digital counters for the two sentry units read '0' and '10' respectively. Less than a seconds worth of firing.

RIPLEY: Yeah, but they don't know that. They're probably looking for other ways to get in. That'll take them awhile.

HUDSON: Maybe we got 'em demoralized.

VASQUEZ: Shut up.

HICKS (to Vasquez and Hudson): I want you two walking the perimeter. Move!

Ripley picks up a cup of cold coffee, draining it in one gulp. She looks shaken and tired.