Background story:
The traitors barely got away from the innocent terrorists in ttt_thething, but they were soon forced to land in another laboratory area nearby due to being low on supplies. They thought they were safe there for the moment... What they soon will discover is that the research lab has been evacuated due to a parasite they had dug up from an ice block. The parasite has some alerting features... it makes the carrier traitorous!

The previous laboratory people found out how to build a traitor tester by using four magic cubes which they also had dug out. The cubes were in an ice block and had to be melted out, so they placed the block of ice in their water tower. They were to late, though, and never finished placing the cubes in the tester - which means the cubes are still in the water tower, free for the traitors to use.