When the TARDIS materialises in the Himalayas, the Doctor decides to pay a return visit to the nearby Det-Sen monastery only to be accused of murder.

Jamie and Victoria make their way to the monastery shortly before it is attacked by the Yeti.

While the Doctor and Jamie return to the TARDIS for equipment, the control sphere Jamie brought to the monastery is reactivated.

The Yeti escapes from the monastery and Victoria and Thonmi are accused of assisting it, while the Doctor and Jamie endure a perilous journey back across the mountains.

Victoria falls under the mental influence of Padmasambhva as the Yeti attack in order to drive the monks from the area.

With the Great Intelligence on the verge of becoming corporeal, the Doctor challenges Padmasambhva to a mental battle in order to defeat it.