Eighteen year-old Marshall Lee and 14 yer-old Prince Gumball throws a Boys' Night! A night specifically for boys. Meanwhile, Marshall Lee invites the two boys' best friend, Fionna, a girl. Marshall discovers that she's a girl, the night of the event. How will he work it out without trashing the ten year-old girl's mind? Find out how a vampire goes a little too scared of a human girl.