Lanzarote, 1985. Archaeologist Howard Foster raises a strange metal artefact from the sea floor. But how is it linked to the signal the TARDIS received? Why is Turlough suddenly so worried? And why is Kamelion acting so erratically?

Barbara Shelley, Dallas Adams, Edward Highmore, James Bate, Jonathon Caplan, Michael Bangerter, Peter Wyngarde, Simon Sutton