Danger at Ocean Deep is the 22nd produced, and the 19th broadcast, episode, of the British television series Thunderbirds.
When the tanker Ocean Pioneer I disappears into a mysterious fog-bank in the Mediterranean Sea - and subsequently explodes (with no survivors) - Jeff Tracy sets Brains and Lady Penelope Creighton-Ward, each working separately, the task of discovering what happened and why. There's good reason to be concerned: a sister ship, Ocean Pioneer II, has just been launched, and could potentially suffer the same fate. Brains and Tin-Tin finally pinpoint the cause: a literally-explosive chemical reaction between the ship's cargo of liquid Alsterene, and OD60, an organic substance found only in certain undersea locations - including the Mediterranean!
- This episode is noteworthy for featuring John Tracy's first (and only) on-air rescue mission in which he directly participates. While at home on leave from his bi-monthly duties on Thunderbird 5, John gets the call to go with Virgil aboard Thunderbird 2, to support Scott with evacuating the OPII crew before the endangered vessel explodes...
Danger at Ocean Deep on Thunderbirds Wiki: