While the Doctor begins a murder investigation in a besieged fortress, Bernice finds herself drawn to an embittered mercenary who has made the heretics’ fight his own. And both time travellers realize that to leave history unchanged they may have to sacrifice far more than their lives.
During the Doctor’s investigation into a siege at a fortress, Bernice gravitates towards a resentful mercenary who has taken up the heretics’ cause. Both time travelers understand that to keep history intact, they may need to give up much more than their lives.