Cato forced himself on, knowing that to stop would be to invite a merciless death. The sword weighed heavily in his hand, but he tightened his grip and ran on. A mile short of the gateway he came across a narrow stream meandering across the small plain in front of Calleva. Before he realised what was happening Cato stumbled on the loose earth hanging over the edge of the stream and splashed down into the shallow water. The sudden shock of the cold current jolted his senses. With a great effort of will he scrambled on to his knees and looked for his sword which had slipped from his grasp in the fall. The blade glimmered beneath the glassy surface several feet away. Cato was about to reach for it when he heard a horse close by. A shadow wavered on the far side of the stream, and Cato lowered himself back into the water, pressing his body close to the bank just beneath the overhang of loose earth. An instant later there was the breathless champing of a hard-ridden horse immediately above him. A small avalanche of pebbles and loose earth cascaded into the water beside Cato. On the far bank was the faint shadow of the horse and rider, and Cato stilled his breathing. A fluke ripple in the surface of the stream refracted a strong shaft of light on to the blade of his sword and it gleamed brightly in the water for an instant.

But an instant was enough. The rider slid off the back of his horse and jumped down into the stream, right in front of Cato, sending spray into the centurion’s face. The warrior waded a few paces downstream towards the sword and then Cato realised he would be seen the moment the man picked up the sword and turned round. There was not time to think. Cato rose and threw himself on the back of the rider as he bent over the sword. The impact drove both men splashing down. The centurion was on top, and he reached forward, searching for the rider’s throat. He found it, clenched his fingers round the muscular neck and pressed as hard as he could. The rider thrust himself up, erupting from the water in a cascade of glittering spray, hands clawing behind his head, reaching for Cato’s arms. He found them and tried to wrench Cato’s grip free, failed and then reached further back, clawing for his attacker’s face and eyes. Before he could succeed Cato rammed his knee into the small of the man’s back and pulled him sideways into the stream, struggling to push the man’s head beneath the surface.