German historian Michael Hesemann spends fifteen years trying to establish whether the Titulus Crucis, a small wooden plaque kept in a church in Rome, is the actual sign that hung on the cross of Christ, inscribed with his name and crime. The film follows his investigation into the relic's origins, tracing its documented history back through the centuries and weighing the physical evidence against the possibility that it is a clever medieval forgery. Hesemann examines the inscription itself, the Latin, Greek, and Hebrew lettering, and consults the historical record around how such relics were venerated and sometimes fabricated in the medieval period. Church officials, archival documents, and the object's display setting in Rome all factor into the case built on screen. Rather than delivering a flat verdict, the film lays out the competing evidence, the arguments for a first-century origin against the signs that could point to a later invention, and leaves the audience with the same open question that drove Hesemann's fifteen years of research.