Reports of a time disturbance lead the Ninth Doctor to modern-day London, where he discovers a Neanderthal Man, twenty-eight thousand years after his race became extinct. The Doctor must learn the truth about the Osterberg experiment before history is changed forever.

Reports of a time disturbance lead the Ninth Doctor to modern-day London, where he discovers a Neanderthal Man, twenty-eight thousand years after his race became extinct. The Doctor must learn the truth about the Osterberg experiment before history is changed forever.