- "What an extraordinary man. He didn't even touch his tea!"
— Lady Penelope Creighton-Ward
A crooked investor called Warren Grafton tries to recruit Lady Penelope into aiding his scheme to build a cross-country monorail. When Penny informs Jeff, he investigates - but he, Brains, Tin-Tin and Grafton find themselves trapped onboard a fully-automated monorail train, speeding towards a stricken bridge.
- Main article: Brink of Disaster/Storyline
- Main article: Brink of Disaster/Transcript
International Rescue Equipment Used
Non-International Rescue Equipment Used
- The monorail train in this episode uses the same model as the one in The Perils of Penelope. It was constructed by using pieces out of a Meccano bridge set.
- Main article: Brink of Disaster/Goofs
- French: Le monorail; Arrêtez le train
- German: Am Rande des Unglücks
- Spanish: Al Borde del Desastre
- Italian: Una truffa ben organizzata
- Dutch: De dodenrit (TV 1967); De laatste redding (TV 1991); Op het randje (VHS, DVD)
- Dutch (Belgium): Op de rand van een ramp (TV 1975)
- Portuguese: A Beira do Desastre
- Japanese: 恐怖のモノレール