Murder on the Cornish Train

One missing passenger. One dead body. Is it murder on the Cornish train? It is a dark and stormy night when Jeff boards the Cornish sleeper train at Paddington station. As they make their way down the dark British coast, waves crash over the carriages and the wheels rattle in the gale. Arriving in Cornwall the next morning, Jeff discovers one passenger has vanished into thin air. The next day, another is found dead on a windswept beach. Jeff can't accept these are coincidences. Could he hold the clue to catch the killer who boarded the Cornish train?