He tries to execute Mr. Peabody and Sherman because he thinks they are the aristocrats oppressing the common folk of France. He tries to guillotine Mr. Peabody but fail. He is angered about being tricked by a cantaloupe. While Mr. Peabody and Sherman runs in the sewers. Robespierre goes a sword fight with Mr. Peabody, and Mr. Peabody wins. Finally, Mr. Peabody and Sherman finally escaped from Robespierre.
The vortex opens which causes the people and object from the past goes right to the present. The police tells Robespierre to back away from the WABAC, he refuses and get tased. Later, he joins in on saying "I'm a dog", adding that he is a poodle.