Warpaint In The West - S1.E20

The train is attacked by American Indians, but Fog, Rigodon, Dix and Bully manage to drive them off. Shortly afterwards, however, Transfer (disguised as one of the Indians) attacks the train's driver and stoker, sending the train careering out of control. Rigodon and Tico, sent to investigate, end up being captured by Indians and, though the train is eventually brought back under control, Fog is not prepared to continue travelling without them.