The best-attested sighting of Black Shuck is also its most dramatic. On 4 August 1577, during a violent thunderstorm, a large black dog was reported to have burst into the parish church of Bungay, Suffolk, running the length of the nave, killing a man and a boy where they knelt and leaving a third worshipper scorched, in the language of the time, "as a piece of leather in a hot fire." The same storm, and reportedly the same or a twin beast, struck the church at Blythburgh a few miles away, where scorch marks on the north door, still shown to visitors today and popularly called "the devil's fingerprints," are attributed to its claws. The episode was recorded within weeks in a printed pamphlet by the clergyman Abraham Fleming, A Straunge and Terrible Wunder, the earliest substantial written source for the legend and the reason the Bungay and Blythburgh incident, rather than any other reported sighting, anchors the tradition historically.
Fleming's pamphlet reads as much as a moral tract on divine punishment for an unrepentant congregation as a straightforward eyewitness report, and modern folklorists generally treat it as an elaborated or partly invented account layered onto a genuine violent storm and a real fire or lightning strike, rather than literal reportage. What is not in serious dispute is that the Bungay and Blythburgh story fixed a black dog firmly in East Anglian memory well before the name Black Shuck is itself attested in print, and gave the later, looser body of sightings a specific date, place and text to be measured against.