In the year 2007, astronauts Jim Parker and Michael Murphy, aboard the space shuttle Charger II, were wrapping up a routine mission. Just prior to reentry, they encountered a mysterious cloudbank in space and were never heard from again. Two years later, a metal box was unearthed at a construction site in St. Louis. In it was a previously unknown, yet apparently authentic, journal of the historic Lewis and Clark expedition written by astronaut Jim Paker. Did Parker and Murphy end up on the Lewis and Clark expedition? And if so, did they alter history or did they save it?