Helga Horse (hu) is reading the little red book (红) in the engine's kitchen ((e)ng2), when she discovers that it is being eaten by a silk worm (纟). She overreacts a little and wants to beat the silk worm with a steel beam (工).
肿
=
中
+
月
:
The moon (月) and Julian Giant Squid (zhu) are playing darts inside of the engine ((e)ng3). Right in his first turn Julian Giant Squid doesn't hit the dart board (中), but instead hits the moon's eye which starts swelling (肿) and develops into a tumor (肿).