Slip, Sach, Chuck , Butch and Whitey suddenly become the Mahoney Collection Agency when they learn that Flynn, stable and second-hand store owner, has owed $250 to Louie, Sweet Shop proprietor, for over two years. Flynn, who has a daughter named Terry) persuades Slip to accept "My Girl," a horse, in payment for the debt. Flynn has been boarding the horse for months but has not been paid. "My Girl" is a really good race horse that is actually owned by racketeer Big Al, who with Weepin' Willie and Swifty, are planning to run the horse in a future race as a ringer for their long-odds and very-slow horse, Tarzana. The Bowery boys learn of this and switch horses. Big Al, Willie and Swifty switch back. This goes on until finally the Boys have "My Girl,", the good horse and Big Al and company have Tarzana, the nag, but think they have "My Girl."