Calvin is building a snow fortress. He says it will be the strongest ever. He tells Hobbes to keep packing in on. The fort will be indestructible. He suggests pouring water over it so it freezes overnight. Their fort will be there until July. The next morning, Dad opens the garage door to back the car out and notices a wall of frozen snow running all across the yard, running right across the driveway. He yells "Where's that kid?!".

From behind his snow fort, Calvin declares the fort can repel any attack. He ducks down, then stands up and leans on the fort. No one is attacking. He puts his hand on the side of his head and laments that he hates this neighborhood.

Calvin is smacked on the back of his head with a snowball. He falls into the snow. He looks around for who the attacker was, but sees no one. He goes into the house. Hobbes is lying on the sofa, reading a comic book. Calvin walks by, snowball on head, and says he's glad Hobbes is inside. Hobbes sheepishly looks up and thinks it's handy to not have boots and a coat to take off.

Calvin yells out that his snow fort makes him invulnerable. He boasts how he can launch a barrage and remain safe from retaliation. Suddenly, a snowball smacks into the back of his head. Hobbes is making another snowball as Calvin complains that he was supposed to attack from the other side of the fort.