|Number in Series||2|
|Air Date||January 7, 2006|
|Next Episode||The Krakken|
|Previous Episode||And Then There Were 10|
Washington B.C. is the second episode of Ben 10.
As they drive to the store Heatblast accidentally sets his seat on fire, and Grandpa Max gets worried about his RV. Gwen comes and shoots Heatblast with a fire extinguisher. Once they catch up to the thieves, Heatblast shoots their car with fire, causing them to crash into a brick wall. Heatblast then scares them into standing by the wall, but transforms back into Ben. When the robbers find out he is just a kid, the cops come in and arrest them. Ben tries to explain that he was the one who caught the bad guys, but the cops dont believe him, leaving Ben upset.kid with a gold Sumo Slammer card. The boy tells him he got it from a box of cereal at the store. While Heatblast is talking to the kid, the Rustbucket comes and Gwen says that the fire was just a distraction for a jewelry store robbery. Heatblast tells the boy that he knew about the cards before leaving with his family.. Somewhere else in town, a man knocks on the evil Dr. Animo's door. When nobody answers, the man walks in rudely. There are cages everywhere with different animals in them. Dr. Animo comes in and the man says that he is the landlord and Animo needs to pay rent. Dr. Animo states that all of his money goes to his research. As the landlord is telling him that he needs to pay, Dr. Animo picks up a helmet type device he calls the Transmodulator. As the landlord laughs, Dr. Animo takes a frog out of its cage and uses his device to transform it into a giant frog twice its size with horns, more eyes, and a longer tounge. The frog then grabs the landlord with its tounge and spits him out against the wall. As Animo talks about how he needs more materials he sees a commercial on the TV about the new M-Mart that is coming out. He now thinks that he needs to go there to get what he needs. Meanwhile, Ben, Gwen, and Max are inside M-Mart looking for food. As Ben goes to the cereal aisle, Grandpa Max complains that he can't find his canned octopus. Gwen tells him that he should buy normal food. After Grandpa Max disagrees and walks off, Gwen goes to see what Ben is up to. She notices a mess of empty cereal boxes all over the aisle. She then sees two small feet coming out of one of the boxes. She pulls Ben as Grey Matter out. Grey Matter says that he is looking for a gold Sumo Slammer card. When an employee comes over, Gwen hides Grey Matter and says that its not her fault, it was Ben's, but he does not believe her. Later, after Ben transformed back, he filled the cart up with cereal boxes. When Grandpa Max asks what they are for, he blames it on Gwen. Grandpa and Gwen yell at him, saying that his obsession with the card has gone to far, but Ben uses his heroic deed of saving the people from a fire as an excuse for deserving the card.
They finally move on. Ben sees a bunch of Sumo Slammer cards and checks them out. While he does that, Grandpa takes Gwen to the pet department, which she hopes isn't going to be where he finds their breakfast. After Ben feels earthquakes, he sees Dr. Animo bursting through the wall on his mutant frog. Ben goes up and asks him what he thinks he's doing. Animo tells Ben not to be a hero and to go and play. When Ben sees that he can't transform, he just runs away. Dr. Animo is then stopped by some guards, but tries to continue. He is then in the section that Gwen and Grandpa Max are in and he turns a nearby bird and hamster into giant mutants. The hamster corners Gwen and Max. Ben hurries, takes a motor scooter, and attracts the hamster's attention. Ben's riding around the store causes some shelves to fall, trapping the hamster. Dr. Animo then steals what he needs and rides off with his mutant pets. The shop owner offers a reward to Ben for doing some good and Ben tries to use that reward to get a gold Sumo Slammer card. However, Grandpa Max hurries and rushes Ben and Gwen into the RV to catch Dr. Animo, so Ben was still unable to get the card.
Now in the Rustbucket, Grandpa Max mentions that their situation is like the good old days, which confuses Ben and Gwen. Max quickly says that he was just a really good plumber. As Ben complains about not getting his reward, Grandpa Max tells him that being a hero is its own reward. Gwen tells them about the research she did, and that Dr. Animo used to be a scientist who was doing weird genetic experiments. His mutants did not win him the award that he desired so much. Remembering what Dr. Animo said in the store about making pre-history, Ben realizes where he went.Once they make it to the Natural History Museum, they see Dr. Animo working on his Transmodulator. When he sees that they are there, he gives a speech about his plans. He then demonstrates how he's going to reanimate dead animals by bringing a nearby mammoth back to life. As the mammoth attacks them, Animo makes his escape. Ben tells them to deal with the doctor while Ben transforms into Four Arms, a tall, red humanoid. As Grandpa Max and Gwen try to catch up with Dr. Animo, they run into the mutant bird. Gwen grabs a nearby spear attacks it, knocking it down. When they catch up, they see Dr. Animo reanimating a T-Rex. Finally, Four Arms defeats the mammoth; however, Dr. Animo leaves riding his T-Rex and the bird kidnaps Gwen as they escape. Four Arms arrives trying to catch the bird. He grabs it and it carries him high up, but he gets shaken off and falls all the way back onto the street. Ben then reverts back to his human self.
Dr. Animo is now on his way to get what he says he truly deserves. A gold Sumo Slammer card also gets stuck between the T-Rex's toes. The bird stops at the top of a monument with a terrified Gwen. She then remembers that she can use her cell phone, as it is an emergency. After Grandpa Max gets the call, he sees Gwen's cell phone crash onto the ground, leaving them worried. Grandpa Max then gives Ben a piece of paper that shows who got the reward instead of Dr. Animo, and that Animo is going to him. Ben turns into a new alien called Stinkfly, which he uses to fly up to save Gwen. As Stinkfly takes Gwen, the bird attacks them trying to get her back, so Stinkfly hurries to give Gwen to Grandpa. Stinkfly finally defeats the bird and then hurries to Dr. Animo.At Kelly industries, Dr. Kelly is giving a tour. Dr. Animo arrives on his T-Rex to get back what's "his". After another speech, his T-Rex attacks Kelly, but before he is eaten, Stinkfly comes in and saves him. After the T-Rex smacks him with his tail, Stinkfly notices the gold Sumo Slammer card. He was going to get it, but then decides to save Kelly again. After he saves Dr. Kelly, Dr. Animo tries to blast Stinkfly with his transmodulator. Stinkfly dodges the attack and shoots some slime at the T-Rex, causing Dr. Animo to drop his reward. Stinkfly steals the Transmodulator and destroys it, returning all of the mutated creatures to normal.
Later, the gang watches Dr. Animo being dragged away by the police. After a while, Ben realizes that Grandpa Max was right and that perhaps saving the city is its own reward. After Gwen thanks him for saving her life, he is rude about it, causing them to fight again as the Rustbucket drives away.
- Ben transforms into Grey Matter, Four Arms, and Stinkfly for the first time.
- Ben and the group meet Dr. Animo for the first time