The Brink of Disaster
It turns out that Ian is the one who has grabbed the Doctor by the throat. Ian isn't quite himself. The Doctor is able to break free and knock Ian to the ground without much in the way of effort.
Ian and Susan recover. Everyone puts their heads into trying to figure out what is going on. Barbara is the one who solves the mystery. It is the TARDIS trying to warn them that something is wrong. The Doctor rejects this idea at first but later sees that she was right.
The Doctor finds a malfunctioning part of the control panel. He fixes it and everything goes back to business as usual aboard the TARDIS.
The TARDIS lands in a snowy region. Barbara and Susan go outside and find a giant footprint.



