Reports of a time disturbance lead theNinth Doctorto modern-day London, where he discovers a Neanderthal Man, twenty-eight thousand years after his race became extinct. A trip back to the dawn of humanity only deepens the mystery: who are these strange humans from the far future now living in the distant past? The Doctor must learn the truth about the Osterberg experiment before history is changed forever.

An adventure featuring the Ninth Doctor as played by Christopher Eccleston and his companion Rose