Arthur Poppington (Woody Harrelson) is sometimes a bit delusional and he makes himself into a superhero who he calls Defendor. Armed only with his homemade gadgets, he decides to take on the world to try to make it a better place to live. He unexpectedly finds himself with a partner in his mission, when he rescues a prostitute by the name of Kat (Kat Dennings). After her rescue Defendor finds himself falling for Kat. As the two work together they find themselves climbing an uphill battle as they chase the biggest crime boss in the city. With nothing to aid them other than their own homemade gadgets, courage and strength, Defendor and Kat try to find a way to preserve justice.