It has been ordained that a select few must from time to time pass over the threshold that divides a mortal's present life from the future. Written well over a century ago, John Uri Lloyd was a visionary who spoke of far distant worlds, dead civilizations, other dimensions and in particular, a world few of us will ever get to visit. A world hidden beneath our feet inside the earth.
Lieutenant Commander Frank Jacklin is blown up in a thorium bomb explosion while on the battleship Alaska. He awakens in the body of Winnie Tompkins who had perpetrated the explosion. As Tompkins, he learns of a plot by German agents to poison Franklin D. Roosevelt and he tries to warn the authorities. He continues to become involved in intrigue until another accident restores Tompkins to his body, leaving Jacklin in the body of a dog.
This, be it understood, is fiction--nothing but fiction--and not, under any circumstances, to be considered as having any truth whatever to it. It's obviously utterly impossible. isn't it?