The film follows the efforts of the polymath Dr. Buckaroo Banzai, a physicist, neurosurgeon, test pilot, and musician, as he tries to save the world by defeating a band of inter-dimensional aliens called Red Lectroids from Planet 10.

References:
https://en.wikipedia.org/wiki/The_Adventures_of_Buckaroo_Banzai_Across_the_8th_Dimension