The episode begins when a cowboy named Mel Gates is by a creek and gets bit by a rattlesnake on the left cheek. Mr Gates fires his gun at the snake which only leads to an on-the-run criminal named Ed Carstairs to come to his aid. However Mr Carstairs has other plans than giving first-aid, he changes ID papers with Gates and assumes his identity. By accident Matt Dillon happens up on the snake bit cowboy and takes him back to Dodge City to be treated by Doc Adams.
Meanwhile, the criminal using the name of Gates has went into Dodge City and became friends with some locals. He is upset to see that Matt has brought the cowboy back to Dodge and feels like the cowboy can identify him. However due to the snake bit the cowboy does not remember anything about his past. Thus making all believe that the cowboy is the criminal that shot a sheriff in a nearby town.
From the following information we get the plot of the show that has the cowboy being accused of a murder he did not commit and the criminal trying to make everyone believe that he is just as concern with justice as anyone else. But the plot seemed to be lacking as parts of the show were long and without action.
Perhaps a sub-plot would have help this show --but that did not happen. Instead we have periods of long dialog and uninteresting conversation to fill in for action.
Could have been better with just some interesting aforethought.