The Head - Season 2 Episode 5 The Bad Seed

An alien bearing a great resemblance to Roy breeched “the security of Technology Incorporated Laboratories and absconded with a container of dangerous experimental energy” (or anti-matter). Pasquale Mendoza alerts Jim and Roy to these events when he comes knocking, assuming that it was Roy who was responsible for the theft… but soon Jim and Roy spot another man with an unusually large cranium – which contains Roy’s baby brother, Mark. Mark is supposed to deliver the anti-matter to a race of nasty, green, humanistic aliens who need the substance for fuel, but a botched transaction on the moon leaves Roy as a hostage to the nasty aliens.