First post, so hope I get this right
3rd Doctor - Jon Pertwee
Sarah Janes first adventure
The Doctor is called in by UNIT to investigate when a number of scientists go missing from a top security institute. Following the kidnapping back in time to the Middle Ages, he is unaware that investigative journalist Sarah Jane has stowed aboard the TARDIS.
As events unfold, the Doctor discovers a sinister alien, intent on altering the future of mankind...