The Best Episodes Written By Sylvia Anderson

After intercepting a missile on course for earth, Steve Zodiac and the crew of the XL5 travel to Planet 46 and discover the Subterrains who launch another missile at the earth with Venus trapped inside.

The Fireflash, on its maiden flight from London to Tokyo, is sabotaged by the Hood, a criminal who has learned of the formation of International Rescue, and is unable to land. The Hood's attack is intended to draw out International Rescue so he can record secrets of its machinery for sale to the highest bidder, an attempt thwarted by the intervention of the organization's London Agent.

Following the destruction of a WASP submarine, Troy and Phones are sent to investigate. They are soon captured by an enemy submarine in the form of a gigantic fish, which takes them to the underwater city Titanica. There, they meet Titan for the first time.

SHADO engages in its first battle with the enemy. Sky One cripples an alien ship which crash-lands in a lake. Straker's team capture its pilot, a strange blue-skinned humanoid - and the grim secret behind the aliens' are revealed.