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Aliens from another realm, planet or otherwise seem to have invaded a small area of Devon by the name of Dingly Brooke. They have disguised themselves as human beings but they are not human at all, and are able to travel through time and space using a unique chemistry found only in their blood.
Perceval Crookshank is an Evil Sea Captain in the year 1780 on board his vessel HMS Thunderheart and his brother Elijah , works on the ship but is always in his brothers shadow and is bullied by him terribly. When the sailors try to revolt against and kill the Captain, their plans are brought down because Perceval is too powerful for them. Their leader , first officer, Mr Knox is humiliated and arrested for mutiny.
In thier travels to the future. in our time, Scientist Braxton Knox, a descendent of Mr Knox from 1780 recommends they are killed. They are a problem to the existence of the human race.
Complications arise when it is discovered Perceval has fallen for a mortal woman from our time and she is pregnant.