Overview
In a Mars base, the inhabitants are being infected by a mysterious water creature which takes over its victims. The Doctor is thrust into the middle of this catastrophe, knowing a larger one is waiting around the corner.
| Actor | Age then | Age now | |
|---|---|---|---|
 | 38 | 54 | |
 | 59 | 74 | |
 | 49 | 65 | |
 | 33 | 49 | |
 | 26 | 42 | |
 | - | - | |
 | - | - | |
 | 37 | 53 | |
 | - | - | |
 | 37 | 53 |