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.
It's now summertime which gives the gang a chance to have fun in the pool. But Puppycorn is afraid of the deep end, so Unikitty and the rest try to help him and show him how cool the deep end is, but ...