Classification
Item #: SCP-[...]; Containment Class: Euclid (Unpredictable); Clearance Level: 3 (Confidential); Disruption Class: Keneq (Extended to a number of people roughly defined as a city); Risk Class: Warning (Moderate to significant effect)
Special Containment Procedures
Due to the complex and unpredictable nature of SCP-[...], a multi-layered containment strategy has been implemented. The affected train station has been condemned and cordoned off, with a cover story citing biohazard contamination. All individuals attempting to access the station are to be redirected, and if necessary, administered Class A amnestics to prevent further breaches.

Level 3 Foundation personnel are to monitor the station's perimeter and prevent any unauthorized access. In addition, a network of hidden cameras and motion detectors has been installed to track the movement of SCP-[...]-1 and detect any potential breaches.
Description
SCP-[...] is an anomalous phenomenon affecting a standard passenger train, designated SCP-[...]-1, and the station it leads to, designated SCP-[...]-2. Initially, SCP-[...]-1 appears to be a typical commuter train with no discernible anomalous properties. However, upon departing from its initial station, located under █████ Street, Line ██ of ███████ City Metro, it enters a pocket dimension, at which point its anomalous characteristics become apparent.

Upon departing from the initial station, passengers on SCP-[...]-1 will experience a sudden and intense emetic effect, characterized by severe nausea and vomiting. This effect is believed to be triggered by the train's transition into the pocket dimension.

Once SCP-[...]-1 enters the pocket dimension, it will continue to move indefinitely, even with the controls being in the off position. The only means of stopping the train and accessing SCP-[...]-2 is by solving a complex logic puzzle, the instructions for which are displayed on a poster in the last functional train car. Failure to solve the puzzle correctly will result in the catastrophic explosion of SCP-[...]-1, causing all passengers to cease and the train to restart its journey from the initial station. The logic puzzle required to stop SCP-[...]-1 is not fixed and will change with each iteration.

SCP-[...]-2 is a seemingly abandoned station located within the pocket dimension. It lacks any visible means of entrance beyond SCP-[...]-1. The station is surrounded by condemned, biohazard signs and degrading infrastructure, and all attempts to access it through conventional means have been unsuccessful.

The staircases and tunnels in SCP-[...]-2 lead outside the pocket dimension, returning to the initial station, but with a significant temporal discrepancy: one year will have passed, and the closest relatives of the individual in question will have deceased. This effect is believed to be a result of the pocket dimension's ability to cause a localized distortion of the current timeline.

SCP-[...] exhibits a unique behavior regarding its passengers. Couples or individuals who form strong emotional bonds during the journey will become isolated from other passengers, who will disappear into separate instances of SCP-[...]-1. This effect ensures that the affected individuals remain together, alone in the train car, regardless of the initial number of passengers.

The last car of SCP-[...]-1 is consistently found to be severely damaged, with the interior exposed to the surrounding tunnel. The cause of this damage remains unknown.