Homeowners spent $600,000 on a Hail Mary to save their beachfront homes from flooding. The sand dune collapsed after 3 days, and saved the homes, but was it worth it?

• Salisbury Beach residents pooled funds for a sand dune to protect their homes from coastal erosion.
• But "king" high tides washed away half of the human-made dune after only three days.
• An ocean engineer says the dune did exactly what it was meant to do.

Residents of Salisbury Beach, Massachusetts spent over half a million dollars on a last-ditch effort to save their homes from flooding. But after just three days, the sea had washed most of their Hail Mary away.