Somewhere beneath the traffic of Philadelphia, embedded in asphalt, are messages that no one has ever fully explained: the Toynbee Tiles. Dr. Helena Marsh, urban folklorist and years-long investigator of the tiles, walks Sterling through the cryptic inscriptions, the reclusive suspect, and the question that still doesn't have an answer — why Jupiter?

Tonight's Numbers Station Puzzler: crack the broadcast, then email your answer and the episode number (episode 55) to [email protected] for a shot at a secret line to the show.

Presented by Double Secret Labs — we do science so you don't have to.

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