A double gunshot murder occurred in the first-class train car where Holmes and Watson were present. The victims were an elderly couple in compartment no.2, accompanied by a visibly terrified young woman. Initial investigation revealed empty compartments no.3 and no.4, while compartment no.1 housed four male passengers, and an elderly mother with her two daughters occupied compartment no.6. Strangely, a wedge obstructed the sliding door of compartment no.2, leaving a one-inch gap. Coincidentally, the sliding door to compartment no.1 was also stuck closed. These obstructions ruled out the killer being in compartments no.2 or no.1. However, several clues suggested that the killer's accomplice was among the passengers! This case baffled Holmes, as the killer managed to vanish without a trace on a high-speed train. Unbeknownst to all, the motive behind this double murder stemmed from a decades-long deep-seated grudge!
