Death Line

Late one night at Russell Square station, Patricia and her American exchange boyfriend Alex discover an unconscious man in the stairwell. They worry he might be diabetic and check his wallet, learning his name as James Manfred, OBE. They inform a policeman, but Manfred has vanished by the time help arrives.

Inspector Calhoun is put on the case and questions Alex and Patricia about the man’s disappearance. He hints that the couple may have robbed him rather than helped him, setting a tense tone for the investigation.

Calhoun’s colleague recounts the London Underground’s brutal Victorian past and a legend that a group of descendants survived below ground after a 1892 cave-in. The story foreshadows a hidden danger beneath the city.

In a stark flashback, the last surviving members of a railway-working family watch their pregnant partner die. They survive by feeding on patrons, establishing a generations-long underground cannibal lineage.

In an empty underground chamber, James Manfred’s body lies mutilated. The mysterious figure then enters a murderous rage, slaughtering three maintenance workers who happen upon the scene.

That evening, the couple catch a train home and get off at Holborn station. Patricia realizes she left her textbooks on the train; Alex tries to retrieve them, but the doors close before he can exit, and Patricia tells him she’ll meet him at home.

After the train departs, the cannibal attacks Patricia in the tunnel and she struggles to escape. She manages to break free and continues to flee through the underground corridors.

Alex returns to Holborn station and ventures into the abandoned area of the Underground. He uncovers remnants of miners who worked there over a century ago, linking the current danger to the old tunnels.

Patricia awakens in the cannibal’s lair, finding him aphasic but able to utter the single phrase 'mind the doors.' She fights him and escapes into a tunnel, while he becomes angry and violent when he cannot communicate.

Alex locates Patricia and the cannibal, and the two engage in a brutal struggle. Alex lands a heavy kick that seriously wounds the cannibal, who staggers toward a passageway.

Calhoun and other detectives locate Alex and Patricia and sweep the abandoned section, uncovering a room filled with corpses laid in bunk beds—the generations of underground survivors. The cannibal is bleeding and appears dead, before there are hints he may yet survive.

The detectives bring Alex and Patricia back to the station platform and prepare to head to the surface. After they depart, the cannibal is heard screaming 'mind the doors' once more as the credits roll, leaving the fate of the threat unresolved.