Tim works at a hush hush government lab. One day, he comes home with a bad stain on his work shirt. He puts the shirt in the laundry hamper, showers, and changes. During dinner, Tim, his wife, and son hear odd noises and discover that the boy's book report on "A Tale of Two Cities" has grown to be ten feet tall and hungry. It also seems to have eaten the dog in one gulp, as he can be seen moving in the thing's "belly."
Wondering how to get help without putting anyone else in danger, they notice a yellow spot along the bottom of "Two Cities." The dog has peed inside the thing and weakened it. He should be safe soon.
They decide water - lots of it - would reduce the thing to a sodden mess and give them time to free the pup and get help. Tim's son's Super Soaker comes to good use. He fires incessantly at the thing, yelling, "Give me back my dog!" The dog falls from Two Cities before the report itself collapses into a soaked mess.
People from Tim's work reluctantly (it is a Sunday, after all - and the game is on) come and take Two Cities away.
The final scene shows Tim's wife sending an email to her son's teacher, asking if - because of governmental secrets she can't really go into - her son might have an extension on his book report assignment.