When 10-year-old Ben Tennyson discovers a mysterious watch, he gains the power to transform into a number of different aliens, each with awesome powers. Ben realises that he must use these powers to help others and stop evildoers, but that doesn't mean he's above a little super powered mischief now and then.

Once upon a time, there was a legendary kingdom which was protected by a courageous hero...his name was Mao Mao!