Taking Care of Business, or Filofax, as it was released in the UK, tells the story of convict and Chicago Cubs fan Jimmy Dworski (Belushi). Jimmy wins tickets to the world series. Unfortunately he still has a couple of days left to serve in prison and the warden won't let him leave and come back. With the help of the other prisoners, Jimmy sneaks out of prison to see the game. On the way, he finds the filofax of uptight yuppie advertising exec Spencer Barnes' (Grodin), which promises a reward for being found. Over the next day, Jimmy takes on the persona of Barnes - staying in Spencer's boss' home, flirting with the boss' daughter, and taking a meeting with a powerful food company magnate (Mako). Spencer's unorthodox methods, such as beating the magnate at tennis and telling him about the poor quality of his food products earns respect from the impressed businessman. Meanwhile, lacking his precious filofax, the real Spencer Barnes is spiraling into the gutter. A series of misunderstandings finally brings Jimmy and Spencer together. Spencer patches his marriage with his wife, who had become exasperated with his overworking. Jimmy sneaks back into prison and finishes his last couple of days, then is released, only to find Spencer waiting to pick him up. With the promise of a beautiful girlfriend and a well-paying job working with Spencer, Jimmy's future looks bright.