A military strategist refuses to accept responsibility for the war games that have mortally wounded his own son. And Margaret develops laryngitis, as she is about to meet her hero, Dr. Chesler.
Tegan steers the TARDIS to the planet Manussa, without meaning to - but why? And is it a coincidence that the planet is about to celebrate the 500th anniversary of the expulsion of the insidious Mara?