In 2005, Ryan Ferguson, then 20 years old, was wrongfully convicted and given a 40-year prison sentence. “dream/killer” chronicles the decade-long crusade by his father, Bill, to establish Ryan’s innocence. The documentary is rich with fascinating personalities, including the dubious District Attorney Kevin Crane, the bewildered witness Chuck Erickson, and the formidable Chicago lawyer Kathleen Zellner. It highlights the justice system’s significant flaws while also showcasing its potential for remarkable effectiveness.