The Brigadier calls in a full UNIT force to deal with the giant maggots while the Doctor infiltrates Global Chemicals to find out what is really going on.
| Name | Type | Role | |
|---|---|---|---|
| Robert Sloman, Barry Letts | Writer | ||
| Tony Adams | Guest Star | ||
| Ben Howard | Guest Star | ||
| Brian Justice | Guest Star | ||
| Jean Burgess | Guest Star | ||
| Ray Handy | Guest Star | ||
| Michael E. Briant | Director |