In April 1968, Conservative MP Enoch Powell stood before a Birmingham audience and warned that mass immigration would leave Britain's streets running with blood, borrowing the image from Virgil's line about the Tiber "foaming with much blood." Within hours Edward Heath sacked him from the Shadow Cabinet, and the speech split the country into those who called him a prophet and those who called him a racist. Filmmaker Denys Blakeway revisits the speech four decades on, tracing what Powell actually argued against what the public remembered, and asking why the inflammatory language crowded out the substance of his case. The film follows the speech's afterlife through Britain's immigration policy debates and asks what drove a mainstream politician to say it in the first place. Archive material and interviews reconstruct the reaction of 1968, from dockworkers marching in Powell's support to the political establishment's scramble to distance itself, leaving the argument over his legacy unresolved.