For reasons of state, Princess Thyra of Swendbord is betrothed to the King of Chekia, a small but politically important kingdom on the shores of the Mediterranean.  Harry Vane, the Duke of Chevenix, envoy of the King of England, arrives in Chekia and falls in love with Thyra.

On the wedding day, a revolution occurs followed by a red reign of terror.  The king is killed, and Thyra is carried off by Gigberto, the rebel leader.  Gigberto and Thyra are captured and imprisoned by the rebels and sentenced to die together.  Harry substitutes himself for Gigberto, and he and Thyra are tied together and thrown into the bay.  Harry frees their bonds and, supporting Thyra, swims to his nearby yacht, where Thyra declares her love.