That uncertainty is, in a sense, the whole story. A souterrain is an underground passage or chamber, typically constructed during the early medieval period in Ireland, often used for storage, refuge, or ventilation. They are found across the country in considerable numbers, but this one exists only as a rumour hardened into tradition, with no visible surface trace to confirm or deny it.

The tradition was recorded by McCaffrey in 1952, who noted that local knowledge held there to be a souterrain in the centre of the cashel, a type of circular stone enclosure associated with early medieval settlement. The cashel itself survives, but whatever may lie beneath its ground has left no mark above it. Whether it was filled in, collapsed without trace, or was simply never there, the record cannot say. What remains is the neighbourhood memory of it, preserved long enough to be written down, and now lodged in the gap between what people once believed they knew and what archaeology has so far found.