In 589 a great flood of the Tiber sent a torrent of water rushing through Rome. According to Gregory of Tours, the floodwaters carried some remarkable detritus: several dying serpents and, perhaps most strikingly, the corpse of a dragon. The flooding was soon followed by plague and the death of a pope. This remarkable chain of events leaves us with puzzling questions: What significance would Gregory have located in such a narrative? For a modern reader, the account (apart from its dragon) reads like a description of a natural disaster. Yet how did people in the early Middle Ages themselves perceive such events? This article argues that, in making sense of the disasters at Rome in 589, Gregory revealed something of his historical consciousness: drawing on both biblical imagery and pagan historiography, Gregory struggled to identify appropriate objects of both blame and succor in the wake of calamity.