‘Voyage of the Damned’ establishes that there is a race of human looking aliens elsewhere who have fascination for Earth and its history. This could be a similar tour, this time emulating the experience of the Orient Express. In which case this adventure could take place in the early 21st century, the Doctor taking Clara on a trip through space not time (making her phone call to Danny less complicated).
The Orient Express itself travels through space on hyperspace ribbons. Hyperspace, a concept once dismissed as absurd by the 4th Doctor, typically is a different plane than normal space. Since the Orient Express does appear to be in normal space it could be that rails are the only thing in hyperspace, allowing it to move faster than the speed of light.
It isn’t clear if the train is generating the hyperspace ribbons itself and if it is whether it has to follow a set route or whether it can lay down new hyperspace ribbons to navigate. If the train doesn’t create the hyperspace ribbons did another party have to lay the route and are these rails regulated?
Quell indicates that anyone who spreads rumours about the deaths will be let off at the next station, indicating that the train does stop along its route. The writer revealed that in the original outline the train stopped at several wonders of the universe.
This is important if you want to set further adventures on the train. It gives you the opportunity to take the PCs to a variety of exciting locations, with a few hours to explore before the train takes them on to their next destination.
The passengers on the train all dress and act in the style of the 1920s. Either this is reflective of their culture or they are trying to stay in period to get the true Orient Express experience. If the latter were true they are certainly dedicated, staying in character even when people start dying.
Notably the passengers and crew all appear human. This would suggest either that this culture doesn’t mix with other species or they are not rich enough to afford passage on the train (and their presence as staff would lower the tone).
The culture does employ cybernetics and Mrs Pitt makes use of Excelsior Life Extender chair. The medical equipment revealed in the lab later is able to complete rapid and thorough medical scans. The fact that no one is surprised by its functions would indicate that it is an established piece of medical equipment.
While the lab equipment probably isn’t standard it would make sense for the train to have some medical facilities or at least one member of staff with medical training. There does appear to be a doctor to attend to Mrs Pitt but he could just be part of the group of experts that were assembled to study the Foretold.
Many of the crew and passengers were actually hard light holograms. This would suggest that they have a physical presence but were projections. Quell is surprised by this so this isn’t standard but if the technology is available it would make logistical sense to use it. It would mean that there could be staff on call 24 hours a day and they wouldn’t need to eat or sleep.
Most likely the hard light holograms could only be projected within the train itself. This would prevent a train from being entirely staffed by holograms, as carrying bags and supplies on and off the train would be necessary at their stops.
We can be reasonably sure that the kitchen staff were alive, since one falls victim to the Foretold and the rest are ejected into the cold of space. Why were they real when most of the other staff were holograms? Could it be that artificial creations lack the ability to cook?
Gus is an example of this cultures level of AI. It isn’t clear how much of the direction that he gives to the captured scientists and his methods to coheres them comes from his own programming and how much is being remotely instructed to him by his master.
When the deception is revealed Perkin suggests that the vanishing guests might have been taken by a teleporter. He might have been theorising but it sounds as if that technology does exist in this culture. Did the train have a teleporter in case someone fell off the train or the passengers needed to make an emergency escape?
Historically Quell indicates that there was a war, one in which his squad was bombed. The fact that he escaped without a scratch indicates that it wasn’t weapons of mass destruction that were used in this conflict. Given the 1920s feel of the era this war could be very similar to World War I. The injuries caused by the conflict could have led to the increased use of cybernetic technology.
The Orient Express and the culture provided allows for many 1920s style adventures but within the context of a science fiction setting. A campaign could be built around the adventures of the crew and passengers, with a rotating cast of NPCs.
Just as with the original Orient Express exciting events don’t just occur at where the train comes to a stop. Galactic events, such as further conflicts, could change or close routes that the train takes.
In addition to murder mystery plots, which ‘Mummy on the Orient Express’ sort of emulates, but it could be the good basis for a disaster adventure. Technical failure and sabotage could leave the train stranded, with dwindling life support.
An adventure could concentrate on the drama and tension resulting from a group of strangers forced to spend extended periods with strangers, even in the luxury of the Orient Express. Things can get very tense if two parties who have every reason to hate each other find themselves sharing a dining car with their enemy.