A large businessman by the name of Oily profits off fluctuating gas prices by buying low and selling back high to local stores. While Oily does threaten hesitant shop owners, Dick Tracy doesn’t hear of this and is forced to let Oily go when his lawyer Slick points out buying low and selling high is not illegal. The money-making scheme loses some of its luster to Oily though when he finds out he’s not actually breaking any laws and he asks his lawyer to come up with a better scheme. Slick suggests they steal gasoline from a coastline refinery, using local wind turbines to power the siphoning pumps.
Meanwhile, at Leafy Dale Asylum, patient #245 has seen Man of La Mancha one to many times and thinks he is Don Quixote. Calling himself Don Quick Oatie he leaves the asylum wearing armor and armed with a broomstick. Finding himself a horse he comes across B.O. Plenty who is out looking for money for Christmas. Claiming B.O. is Sancho Panza, he enlists B.O. to ride a burro alongside him as they engage the “Giants” (windmills) along the shore.
Tracy has received reports that the missing patient may have kidnapped B.O. and goes looking for the two but instead comes across tanker trucks siphoning fuel from a fuel line. He and Lizz investigate and are captured by a thug named Sludge who is operating the truck. Sludge plans to take the two back to Oily and the two are placed inside the trucks tank.
Don Quick Oatie spies the tanker truck and decides it is a dragon and attacks it with a piece of fence, which is his “Broadsword.” He seems to cause no harm before he is unhorsed, but in fact he cuts the brake line and the tanker crashes into an auto garage once it makes it to the edge of town. Tracy and Lizz escape out of an open hatch in the tank and hide themselves in the garage, calling for reinforcements when Oily and his men begin to search the building to kill Dick Tracy. Don Quick Oatie rides to save the day, spearing an electrical box with his broom and starting a fire. The tanker truck explodes, with Lizz, Tracy, Oily and Slick barely escaping.
Oily and Slick run into a blizzard, trying to get away and Tracy and Sam follow their trail. The two criminals seek safety in the interior of a wind turbine, at the top near the blades. Quick Oatie, who has been wandering around on his horse, dejected, spies the windmill and attacks it, getting hooked on a blade and spun around. Oily sends Slick out to investigate the sound and Slick falls to his death, landing on a service building next to the windmill which catches both structures on fire. On fire and burning quick, the windmill collapses, slinging Don Quick Oatie off into the snow while Oily is killed in the fire. After a long search, Tracy finds Don Quick Oatie has survived his fall and returned to his Asylum, caring little for the days events.
The money poor B.O. and Gertie Plenty win $500,000 in the lottery. Against all advice, B.O. takes the money in cash and head on vacation to Washington D.C. Meanwhile a new terrorism specialist named Bob Bardier is assigned to Tracy’s squad but Tracy is more concerned about B.O. and his money. In Washington, a terrorist cell led by Al Kinda is working to gather money to send to Afghanistan. He sends a subordinate named Lottie Latte, a hulking woman who often works to improve her looks to pick up the Plentys at the airport. After picking up the couple, who think she is there to assist them, the limo smashes into the lead car of the presidents convoy. B.O.’s money bags are mixed up with government bags, and they leave with the wrong bags without talking to the Secret Service.
They finally reach Al Kinda’s “bed and breakfast”, which turns out to be a dingy apartment. Al Kinda discovers their bags hold government missile launch codes. He orders Lotte to execute the Plentys in the basement, but she pretends to do the murder, leaving them alive. B.O. sneaks upstairs and knocks Al Kinda out with a baseball bat while Lotte looks on with a smile. The Plentys then run to the cops with the code case.
Al Kinda wakes up and in an angry fit shoots Lotte and carjacks a taxi to hunt down the Plentys. Back with the police, the two out of towners are reunited with Tracy and their money, while the code cases are returned to the government authorities. Tracy and the Plentys then go out to find Al Kinda again, and hail a cab that happens to be driven by Al. Al and Tracy get into a fight, with Al getting the upper hand and running away with B.O.’s cash bag and Tracy’s wrist genie. Tracy has the genie tracked by GPS and tracks Al Kinda to the Capitol building, which is closed for the night.
Al Kinda meets a hiding friend in the Capitol, who hands him a bomb, then Tracy chases him outside, on the ledge of the Capitol’s dome. The two trade gunshots, a Tracy loses his gun while Al’s bag is punctured and cash flies out into the wind. Al Kinda goes to finish Tracy off when a shot fired from down below hits the terrorist in the middle of the chest and he falls to his death. The shot, it turns out, was fired by Lottie Latte, who is still alive, having been saved by a beauty compact. Lottie reveals she actually works for the National Security Agency.
Half of the Plenty’s winnings are recovered, and after receiving a medal from the President the three fly home with Dick Tracy with plans to build an indoor bathroom in Plenty household.
Technology industrialist Diet Smith calls Dick Tracy and introduces him to Dr. Figment Froid, one of his scientists. To Tracy’s utter amazement, Figment has created a hand held mind reading device and Diet wants Tracy to test it out as a crime fighting tool. Tracy takes it to the office, learning Sam’s political leanings, Lizz’s early crush on him, and and amazing thing about Chief Patton. All three are quite angry and kick him out of the office.
Suprised at their rejection of the new device, Tracy goes home where Tess has just inherited five million dollars from her rich Uncle Peter. Dr. Froid we learn, has been listening in to the thoughts of everyone back at his laboratory and decides this is a perfect time to test the other half of the device, which he triggers to scramble Tess and Dick’s memory. Then he calls the bank and arranges for the full five million to be delivered to the Tracy household where he swipes it from Tess, using his device to again scramble their brains.
Still, Dick is starting to adapt to the mental confusion, and follows Froid’s car back to Diet Smith Industries. Remembering who Froid is, the two get into a brawl and Dick ties up the evil doctor. Diet Smith, security and the police arrive and Tracy uses the device to read Froid’s mind, revealing to everyone the depth of his plot. Once the ordeal is finished, Dick and Tess decide to donate the bulk of the inheritence to Alzheimers Research.