Flicka, the beloved horse of young Ken McLaughlin (Roddy McDowall), has given birth to a son. But instead of taking after the calm and collected Flicka, the colt, which Ken names Thunderhead, takes after his wild albino father. Despite Thunderhead's wild streak and rebellious spirit, Ken and his father, Rob (Preston Foster), try to break the wild stallion and make it into a prized racing horse. But Thunderhead's wild nature may be too much for either of them to tame.