The first completely automated Bolo, designed to operate normally without a man on board, was the landmark XV Model M, which performed remarkably well.

However, the always-present possibility of capture and use of a Bolo by an enemy was a constant source of anxiety to military leaders and, in time, gave rise to the next and final major advance in Bolo technology: the self-directing and self-aware Mark XX Model B Bolo, Tremendous.

But what happens when a self-aware fighting machine decides to go rogue?