Overthrown and driven into exile, the king of Scandia has fled to Britain with his wife and son, Prince Valiant (Wagner). As a young man, Val goes to King Arthur's court, where he is befriended by Sir Gawain (sterling Hayden) and trains to be become a knight of the round table. Val also falls in love with a beautiful princess (Leigh) and faces the treachery of the mysterious Black Knight, who is scheming to betray Val's family.