Aboard the luxurious high-speed express “Freccia d’oro,” a jeweller carrying precious gems is targeted by thieves who take over the train, disabling alarms and barricading themselves in the baggage car. Meanwhile, a bridge ahead has collapsed, and the train is unaware due to the thieves’ isolation of the locomotive. Panic ensues among the passengers. Just as disaster looms, the young engineer sees a glowing cross in the fog, prompting him to stop the train in time. The cross is revealed to be a rosary from his mother, reflecting off the headlight. This divine sign saves everyone, and the thieves are captured.