Trini has been standing in the freezing cold, threatening to become almost as sick as Marc. Lisa gives a demonstration on feeling hot and cold. But the biggest surprise comes when Lisa brings in Vicky Johnson, an engineer who designs life-support systems for astronauts. On location: Lisa witnesses an infrared camera. Trini learns about protecting the human body from the cold while climbing a mountain.ANIMATION: Fahrenheit vs. Celsius.THE BLOODHOUND GANG: ""The Case of the Secret Message, Part One."" Vikki recovers a lady's purse, which contains only a message written in salt-water solution. (Concludes in next episode.)

The desert and polar regions demonstrate how plants and animals react to extreme heat or cold. The Bloodhound Gang unlocks ""The Case of the Secret Message.""

Lisa is bitter over her cold. As Marc and Trini try to warm her spirits, Lisa thinks back to her visits with the motorcyclist and the hot-air balloons. The Bloodhound Gang must work quickly to crack ""The Case of The One-Ton Jewel.""