Jake Blues, a blues musician and petty criminal, is released on parole after serving three years of a five-year sentence for armed robbery. His brother Elwood picks him up in a battered former police car, famously known as the Bluesmobile. On their way, Elwood demonstrates the car's surprising capabilities, even propelling it over an open drawbridge.

The brothers head to the Catholic orphanage where they were raised and learn from Sister Mary Stigmata that the orphanage is on the verge of closure due to $5,000 in unpaid property taxes. Later, while attending a sermon by Reverend Cleophus James at the Triple Rock Baptist Church, Jake has a sudden epiphany. He hatches a plan to save the orphanage by reuniting their old band, the Blues Brothers—which disbanded when Jake was incarcerated—and raising the necessary money through live performances.