Brink of Disaster is the 11th produced, and the 22nd broadcast, episode of the British television series Thunderbirds.
Lady Penelope Creighton-Ward is entertaining a visitor to tea: one Warren Grafton, a go-getting American businessman seeking investors in his Pacific-Atlantic Monorail enterprise. "I have a friend who may be interested," she tells him, "I'll see he contacts you..."
"He" is Jeff Tracy, himself a retired businessman; and as Penny describes Grafton's project - along with her own concerns about it - he does in fact evince some interest and agrees to a meeting, with Tin-Tin Kyrano and Brains along as his advisors.
But not all goes off as advertised - Parker has his own suspicions about the company Grafton keeps; while the planned demonstration of the new monorail reveals even more about Grafton himself...
Brink of Disaster on Thunderbirds Wiki: http://thunderbirds.fandom.com/wiki/Brink_Of_Disaster