We examine the enduring mystery of the Pied Piper of Hamelin legend, which describes the disappearance of 130 children from the German town in 1284, after the town reneged on a debt to the Piper for removing rats. The texts highlight historical evidence from town records and plaques that confirm the event's date and the number of missing children, while noting that the element of rats was a later addition to the folklore. A significant portion of the material focuses on the migration theory, suggesting the Piper was a recruiter, or Lokator, luring Hamelin's youth to settle new lands in Eastern Europe during the medieval Ostsiedlung expansion. This theory is supported by linguistic evidence linking family and place names from Hamelin to regions near Berlin and Brandenburg. Other explanations for the children's disappearance are also discussed, including theories involving a massacre, a Children's Crusade, or an outbreak of disease such as murine typhus or dance mania.