2. Episode 2

As the situation worsens at the refinery, Chief Robson refuses to halt the gas flow. Elsewhere, the weed extends its influence and Mrs Harris receives sinister visitors.

3. Episode 3

Despite the mounting evidence, Chief Robson refuses to acknowledge that matters have escalated beyond his ability to control them.

4. Episode 4

Investigating the impeller shaft, Van Lutyens is overwhelmed by the weed creature. A call comes from one of the off-shore rigs - the weed creatures are attacking and taking over!

5. Episode 5

As the weed breaks into the Pipeline Room at the refinery, the deranged Chief Robson kidnaps Victoria in a helicopter and heads for the Control Rig.

6. Episode 6

The Weed has complete control of Chief Robson and threatens to conquer Earth. The Doctor searches for a means to defeat the creature and believes the answer may be Victoria...