This is Mickey Rooney's first true adult role, just a year after his final appearance as Andy Hardy until a final film in the 1960s. This entry has lots going for it, not the least being a terrific performance by Rooney as the title character. At age 27, Rooney was trying to rid himself of MGM's image and McCoy was probably a godsend role for him, bridging the squeaky-clean image that he had with something a bit more adult. Rooney here is still boyish and starts the films as the dutiful son of a no-good drunk father (James Dunn) and a mother who literally works herself to death providing for the family and making excuses for her wastrel of a husband.
The local priest, as an act of charity, tells Rooney and Dunn about a need for a song and dance number to open for a fight that night with the job paying ten dollars. After the fight, Rooney says he'd like a turn at the winner, and he does manage to knock the guy out. This causes someone who sees the fight to take him under his wing and teach him the ropes of the trade. At one point down the line Rooney kills a guy with his punch and that earns him the nickname "Killer".
All the while Mickey's dad is causing problems - drinking heavily, running up big debts to gamblers that eat up the purses that Mickey wins, until his dad sells Mickey's contract to a crooked gambler (Brian Donlevy) who is living a double life that includes a daughter nobody knows about who is attending an elite finishing school (Ann Blythe). Complications ensue, not the least of which is that Rooney's father has a big mouth in the presence of the wrong people about everything that is going on.
Look fast for Shelley Winters in a non-speaking bit as one of Rooney's groupies as he trains for a championship.
What I've described sounds pretty formulaic except maybe for the crooked gambler living a double life, but it is very well done and is an excellent showcase for an adult Rooney in an adult role. He's convincingly hard boiled when he needs to be. The only thing negative I can say is how the conclusion seemed rushed - like the writers really didn't know quite how to end it.
Strangely enough, Rooney and the director of this film had a big argument on the set about how bad Rooney's acting was which caused him to walk off the set. Rooney angrily recalled the incident 50 years later when Robert Osborne interviewed him on Turner Classic Movies. Osborne sat perfectly still while Rooney ranted about the situation, later saying he was afraid Rooney would have hit him if he moved or spoke.
