After witnessing his master's stepfather being murdered by the conniving Phil, a dog named Peter carries messages in and out of prison for his wrongfully convicted owner, Jack. Later, in Mexico, Peter chases down the villain, forcing a confession and saving Jack.
| Actor | Role |
|---|---|
 Eleanor BoardmanBarbara Jane | Barbara Jane |
 Raymond McKeeJack | Jack |
 Earl MetcalfePhil | Phil |
 Paul WeigelThe Stepfather | The Stepfather |
 Edna TichenorThe Painted Lady | The Painted Lady |
| PPeter the GreatHimself | Himself |