Katie and Daniel Hart are siblings in their twenties whose hopelessly childlike demeanors constantly hinder their futile attempts to be grown-ups.
Katie discovers her brother Daniel eating a bowl of ice cream for breakfast, leading to a debate on which of them is more "grown-up".
The seemingly simple task of replacing a burnt-out light bulb proves to be a big challenge for the siblings.
Daniel's earbuds prevent him from hearing Katie screaming, leading her to wonder how helpful he'd be in an emergency.
Daniel asks Katie to pick up her toys, but she refuses.
Katie introduces Daniel to the stray cat she found wandering in their backyard.
After discovering they're out of milk, Katie and Daniel discuss their shared hatred of grocery shopping.
An argument arises after Katie thinks that Daniel is asleep and she changes the TV channel.
A bird flies into Katie's bedroom and she enlists Daniel's help in getting it out.
Katie is overexcited after buying a new chair, but Daniel is less enthusiastic.
Katie tries to trick Daniel into doing her laundry.
Katie and Daniel are assembling a set of toy bricks, but discover that one of the pieces is missing.
Katie and Daniel get locked out of the house and have to find another way in.
Daniel begins to wonder if he and Katie spend too much time together.