Based on

Movies like My Pal Trigger (1946)

Gabby doesn't want to breed his horse the Golden Sovereign with Roy's. When Sovereign and Roy's horse escape, the Sovereign gets shot accidentally by Skoville but Roy is blamed and jailed. A year later Roy returns with Trigger, the son of the Sovereign. When Skoville reveals he was present when the horse was shot, Roy sees an opportunity to clear his name.