Dink, Josh, and Ruth Rose investigate the theft of a great deal of money from the belly of a nearly life-size Tyrannosaurus Rex model that their friend, Jud Wheat, is using to raise money for a dinosaur museum.

Bradley, Brian, Nate, and Lucy enter Polly the pony and Pal the dog in a July 4th pet costume contest, but when Independence Day arrives the animals are nowhere to be found.

As they leave a Fourth of July celebration with the President of the United States, KC and Marshall see unauthorized fireworks at the FBI Building and decide to unmask the culprit and his plans for blackmail.