William Ludlow es un coronel separado de su mujer que vive con sus tres hijos en un gran rancho de Montana, en las colinas de las Montañas Rocosas. La Primera Guerra Mundial y una bella mujer cambiarán el destino de cada uno de ellos para siempre. Sus hijos son el indómito Tristan, el sensato Alfred y el menor Samuel, que acaba de traer al rancho a su bella prometida, Susannah.
A mysterious criminal steals a secret state-of-the-art time machine, intent on destroying America as we know it by changing the past. Our only hope is an unexpected team: a scientist, a soldier and a history professor, who must use the machine's prototype to travel back in time to critical events. While they must make every effort not to affect the past themselves, they must also stay one step ahead of this dangerous fugitive. But can this handpicked team uncover the mystery behind it all and end his destruction before it's too late?
