A Death on the way to Portsmouth

Violet Harper might be fearless when it comes to caring for the dead, but she trembles at the thought of boarding trains-those behemoths of belching smoke and screeching brakes. Nevertheless, she must travel via one of these beasts from Southampton to Portsmouth. Her anxiety turns into horror when a fellow passenger is murdered as the train carriage enters a tunnel. Can Violet discover who the murderer is before the train reaches its next stop? Note: this is a short story, not a full-length novel.