Murder on the Galaxy Express

Humanity had spread out over a small part of the galaxy.  Now several hundred colonies had been established on Earthlike planets around the Milky Way. Of course traveling between these colonies was dangerous and unpleasant. That was until the star trains appeared. These majestic marvels of engineering were reminiscent of a previous, more gracious time in human history.  The greatest of these incredible vehicles was the Galaxy Express. It was the queen among the Star Trains and had an interstellar reputation for comfort and safe passage. That was until the murder happened. A "locked-room" mystery showing the heights someone would go to commit the perfect crime.