When Master Frown starts a prank war with UniKingdom, the friends are ready to strike back. But Unikitty doesn't really understand pranks, thinking they're too mean.

Unikitty takes in a radioactive caterpillar and raises it like a baby, unaware of the havoc it will wreak as a full-grown adult. When Unikitty accidentally invokes an ancient curse, the gang must beat ...