On Aunt Lavinia's request, Sarah Jane Smith and K9 join Dr Warren Martyn and his assistant, Dexter Townsend, on an archaeological dig in Egypt. They have uncovered a hidden city of the Eocenes (identified as such by K9). Dexter is only after the treasures and is killed, but the Eocenes are seeking peaceful co-existence with the humans. Warren agrees to stay so they may exchange cultures and Sarah is given free passage to return home to negotiate their terms. Sarah is optimistic after speaking with the Brigadier. UNIT this time round seems more sympathetic.