In the movie, a lion called Scar murders his brother, Mufasa, who is the Lion King. He makes Mufasa's young son/cub Simba (who is the heir) believe it's his fault he died, and Simba runs away in shame from the kingdom. Scar then takes over the kingdom and it is overrun by his henchmen, the hyenas and the lions suffer while also falsely led to believe that Simba murdered Mufasa. Year later, Simba, who is now grown, returns and fights Scar and wins. Glory is restored to the kingdom, the hyenas are scared away and Simba is the Lion King.

It's literally Hamlet but with lions.