Under the Weather

 is the sixteenth episode of the fourth season and the seventy-third overall.

Synopsis
At Blue Base, Tucker becomes ill. Church and Caboose discuss Tucker's sickness, which apparently he caught when the Sacred Quest team stayed overnight in a swamp. Church suggests the sword's power source could be giving off radiation. Church and Caboose have a reasonably light and friendly discussion regarding the nature of the sword, as Tucker rolls in pain. This friendly discussion even extends to Church mentioning that he would love to "live in [Caboose's] world for about 10 minutes" just for fun.

At Red Base, Simmons persists in trying to enter to relay vital information about the war to the Reds. However, he still meets resistance from Donut and Grif until he unrealistically quickly changes out of his mostly blue armor to his original maroon armor. Apparently Simmons learned this ability because of his extreme shyness, which has led him to never use the base's toilet for the past three years.

Back at Blue Base, Church and Caboose question Andy on what might be causing Tucker's sickness and suggest that he, being a machine (and thus not able to get sick), go into the base, find out what is wrong with Tucker and report back. Since Andy is a bomb, the only solution he can provide is to blow up the base with Tucker inside, killing all the germs and everything around the base in the process. Finally, out of frustration, he tells Church and Caboose that if they want a medical diagnosis, they need to find a doctor. With that, Caboose tells Church, "Please don't do it."

O'Malley and Lopez bicker over who should pick up the telephone that is ringing inside their secret lair (Relic), while Doc decries their bickering. It appears that all three have survived their encounter with the Alien and that O'Malley has continued in his pursuit of taking over the universe. It would seem from Lopez's attitude toward O'Malley all those attempts have failed miserably and this has caused Lopez to become quite cynical and disrespectful toward him.