His cousin Sid calls him a benchwarmer, causing Casey to hit him in the face with his hockey stick out of anger.
On his way home, Casey tosses away all of his hockey equipment, except for his stick, and spots a boy spray-painting graffiti on his building.
Casey tells her he got jumped, causing her to say that she has decided to sell the building and head back to Northampton.
Over the next week, Casey starts training by lifting weights, jogging, hitting a punching bag, and smashing stuff at the local dump with his hockey stick while April O'Neil does a news report on the Lower East Side, a part of the city ruled by the Purple Dragons and other street gangs.
That night, when Casey spots the Purple Dragons mugging a woman, he viciously attacks them until all of them except one are knocked unconscious.
He swoops down and beats one of the thugs unconscious and breaks the other's legs, but before he can finish him off, a man in a trench coat takes his baseball bat.
Mikey takes Casey back to his lair in the sewers, where he is introduced to Leonardo, Raphael, and Donatello.
[1] Banks shot the film over a two-year period while living in Austin, casting his brother as the title character.