Clash on The Big Bridge.

A Odd Stranger Visits The Princesses of Equestria in search of a item of up-most importance.

Luna comes across an item of inmense power in her most recent travels only to be visted by a Mysterious Stranger who vows to claim her prize as his own.

Now with the aide of Celestia herself they must fight hoof over hoof to keep this stranger from not only gaining a new weapon of destruction but also keep the fate of Equestria in balance.