A huge cosmic cloud is reported moving into the outer fringe of the galaxy. Starfleet Command sends the Enterprise to investigate. Sensors indicate it is a strange combination of Matter & Energy. It seems to engulf and feed on the energy of planets. It makes a deliberate course change to head towards the populated planet of Mantilles indicating that it could be intelligent. Kirk sees it as a threat to every planet in the galaxy and if they can't communicate with it and make it stop it will have to be destroyed. Written by
Did You Know?
Though Robert Wesley was played by Barry Russo in the original Star Trek series, James Doohan provided Wesley's voice for this episode. See more
When Commodore Wesley appears on the computer monitor in Kirk's quarters, Wesley's shoulder is visible on another, separate view screen right next to him. See more
Captain James T. Kirk
Judging from the disappearance of Alondra, the cloud lives on the energy it converts from the planets it consumes.
Exactly. It is like a huge bull grazing here and there in the pasture of the universe.