On Sunday morning, June 29, 1919, a group of people assemble at the Boulder depot for a trip into the mountains on the Switzerland Trail of America railroad, unsuspecting what lies in store for them. During the journey into the mountains, past relationships and negative feelings between passengers become apparent. After a lunch stop at the mountain destination, everyone returns to the railroad car for the journey back down the mountain--except for one passenger, who arrives only as the train is leaving. He staggers in through the back door of the railroad car, points toward the others and shouts "You assassin" before collapsing in the aisle, dead from a knife wound. Off-duty police officer, Harry McBride, is determined to solve the murder before the train returns to the Boulder station. Armed with motives from the earlier conversations, he sorts through suspects to find the killer. This historical mystery novel provides a snapshot of the city of Boulder, Colorado, and its narrow-gauge railroad in the early years of the twentieth century.