Thanks To Dollhouse. Nice and concise. Though I hate to lose the locked room mystery aspect of it, the fact that the victim disappears or appears to disappear from a moving train.
Richiev, the diplomat is a pure macguffin and his nationality doesn't matter. All that matters is that everybody agrees he's important.
Tony Edwards, you line reads well but actually deviates from the premise of the script, which is a bit involved. The diplomat, whom the Germans want dead, appears to have been killed. Only the reporter believes he is still alive. If he proves it, this will alert potential assassins. Tough to cram this into a nutshell.
Thanks for all the input. Will work on it.