Carolyn comes down with a bug, and Captain Gregg, dissatisfied with the doctor, concocts his own remedy which sends Mrs. Muir back to the mid-1800's where she is the "ghost" and the very much alive Captain is the only one who can see her.
Mrs. Muir develops a fever, and Captain Gregg takes it upon himself to influence Martha to put Carolyn to bed. He also concocts his own home remedy, laced with plenty of brandy, that gives Carolyn a dream where she's a ghost back in the 1800s haunting a living Captain Gregg during a ball.—statmanjeff