The crew of the Enterprise are undertaking routine tasks when suddenly the ship is struck by some outside force, rendering much of it inoperable and many of the crew stranded in various locations without communication to other sections; later the crew discovers the collision was with a fragment of a quantum filament, and after effecting basic repairs, set course back to the nearest starbase for a full overhaul.
During this, several different sub-plots are followed across the various crew members:
The bridge, at the time of the incident, is only manned by Counselor Troi, Miles O'Brien and Ensign Ro. They find that the anti-matter containment field in Engineering is rapidly fading. Ro suggests that they split the drive section of the Enterprise off to save those in the saucer section, but O'Brien refuses to accept this. Troi agrees, and instead suggests a plan to divert a supply of their minimal power reserves to Engineering to the appropriate panel, hoping that someone there would rectify the situation. This is later done by Commander Riker and Lt. Commander Data. Ro apologizes for considering such a hasty action.
Riker and Data are in Ten Forward along with Worf and a pregnant Keiko O'Brien at the time of the disaster. With several injuries, Riker assigns Ten Forward as a triage area with Worf and Keiko helping. Riker and Data realize that without functioning turbolifts, it would be faster to travel through the Jeffries' tubes to reach Engineering in order to regain control of the ship rather than to try to make it to the bridge. In Engineering, they find that the computer remains offline, and Data offers to use his own positronic brain to gain basic control of ship systems. Riker discovers the operating panel that indicates the containment field failure, and he and Data quickly set up the proper connections to restore it until regular computer operation is restored.
Captain Picard has the dubious honor of giving a guided tour of the ship to three children that won a science fair, a task he has not been looking forward to. They are aboard the turbolift when the accident occurs, and Picard suffers a fractured ankle from the sudden stop. He calms the children down, and to boost their morale, assigns them honorary command roles. With their spirits renewed, Picard and the children start to climb out of the turbolift and up the shaft until they are able to access the lift doors on another floor and climb out safely. Picard comes to appreciate the children and offers to give them another tour once the situation has been resolved.
Doctor Crusher and Lieutenant Commander La Forge are in a cargo bay examining a recent supply of thruster fuel. When the disaster strikes, they are trapped in the bay, and find that a plasma fire has erupted in a nearby panel; it is not only letting off potentially lethal radiation affecting them, but also destabilizing the fuel, risking an explosion. They come up with a plan to depressurize the bay, not only dousing the fire due to lack of oxygen, but also removing the fuel during the explosive depressurization. They safely hold on during this process and eventually reseal the bay with fresh air.
In Ten Forward as they tend to patients, Keiko starts to feel the onset of childbirth, forcing Worf to help her deliver her child despite having only basic medical training. Though the delivery is tense, Keiko's child, Molly, is delivered safely.