During a live broadcast following Guinevere One’s journey to Mars, Earth’s space probe was intercepted by a giant spaceship. On board was a fearsome warrior race, the Sycorax.
One of the aliens, it’s skinless face covered by a bone-like exoskeleton, interrupted the broadcast with a terrifying demand. They were using a vial of A-positive blood from the Guinevere to put one third of the world’s population into a trance and threatened to kill them unless half of the Earth’s inhabitants became their slaves.
A newly-regenerated Tenth Doctor challenged the Sycorax leader to a sword fight with the Earth as the spoils. Although temporarily losing his hand, the Doctor defeated the alien with a nifty use of a satsuma.
Victorious, the Doctor ordered the Sycorax to leave the Earth and never return. However, as their ship was leaving, Prime Minister Harriet Jones instructed Torchwood to shoot it down as a warning against any future alien invasions.