The Cross family is enjoying the perfect Christmas Eve until someone from the Council for Temporal Studies arrives. A time-travel pocket watch lost by one of their operatives has been found ... by none other than Mark Twain! Simon & Elizabeth must go back to 1898 and retrieve the watch before Twain accidentally wreaks havoc on the timeline—altering the fabric of history forever.

Their spirited ten-year-old daughter, Charlotte, joins them on their mission—a train ride across the country and into the very heart of Christmas. But the legendary author is a broken and bitter man, and it just might take a Christmas miracle to save the day. A fast-paced and charming celebration of the season, The Christmas Express is Simon and Elizabeth's most personal, enchanting, and heartfelt adventure yet.