Ron comes home to unexpectedly find his new adopted baby sister named Hana Stoppable in his room. At the same time, he has to take care of a sack of flour for health class. Meanwhile, Kim and Ron team up with Yori to stop Monkey Fist yet again.

After discovering Hana walking on the ceiling, Kim and Ron try to get to the bottom of Hana's secrets. Meanwhile, Monkey Fist finds an ally in Yono the Destroyer as he continues his search for the "secret weapon".

Kim plans on throwing her cousin Larry a surprise birthday party, but she has to keep him busy until the party is ready. Meanwhile, Dementor enlists the help of his brother-in-law to steal Kim's battlesuit.