When a ghost of ancient Pompei is given the chance, he takes it to inhabit the body of a time travelling scientist, complicating an already taut situation. Rick has re-entered Mackenzie Cates' life and their passion has been reborn, but since neither is into menage a' trois, they need to get rid of the two thousand year old ghost living inside him, reunite said ghost and his doomed love in the far flung past, and save the world.