Just when C.A.T. thinks Triton Base is back to normal, an inbound cargo craft radios a mayday. Seems a computer virus has infected the controls, and the ship is on a crash course toward the liquid oxygen fuel depot, a collision that will destroy the base in a fiery inferno. While Commander Zacman and his crew try everything they know to avert disaster, C.A.T. investigates and discovers this virus is its old nemesis from back on Callisto, a malevolent AI now residing in Central and itching for a code-to-code battle to the deletion with C.A.T. It's going to take a miracle to save them, or in this case, an angel.