Thunderbirds Are Go S01E07 - Runaway

A strange malfunction occurs on a high-speed train in Japan, leaving it out of control and unable to stop. Brains comes up with a plan to fix the problem before a disastrous crash occurs - the only problem is that he will have to board the speeding engine himself to pull it off. Scott manages to get the genius on board, where they find the problem is more complicated than they thought.