sentences:  A Seventh Doctor Past Doctor Adventure novel was released with the same title in April 1998, but has an unrelated plot.Written by Jon Pertwee & Reed De Rouen and also known as "The Brain Drain" and "The Labyrinth", this seven-part story was submitted to the production team in the summer of 1970.In the proposed storyline the Doctor poses as a Cambridge don to investigate a series of disappearances.