In Watch Out She's a Mastermind Heiress movie, after growing up in the countryside, 21-year-old Isabella Patton is sent back to her wealthy birth family. Before long, she becomes acquainted with the smoldering (and much older) Oliver Bates, who begins to relentlessly pursue her, oblivious to the fact that she is his fiancée. Meanwhile, Isabella's cousin Eliza, who was raised by the Patton family in her place, is on a desperate mission to turn the whole family against her for good. Unluckily for Eliza, Isabella is a hotshot genius with unparalleled talent in the medical and tech fields, and is able to outduel Eliza at every turn. As Isabella's unique skills are revealed, she wins the support of her five brothers and parents, becoming the crown jewel of the Patton family while always remaining just out of Oliver's grasp.