The intruder was heading towards this table.

The dark figure slipped into the shadows of a small grove forty metres from the bench, then dropped belly down to the ground. Taking one last look to get a bearing, the intruder snaked out of the shadows, face down, heading for the shelter of the table.

Progress was painstakingly slow. This was obviously a trained stalker who knew that any rapid movement would register with the sentry's peripheral vision. As shadows of clouds passed over the park, the crawling figure would move with them, rippling unobtrusively across the short grass, seeming to be just one more moving shadow. The dark green clothing aided concealment. Black would have been too dark and would have created too deep a shadow.

Dark green merged perfectly with the tone of the grass itself.

It took ten minutes to cover the distance to the table. A few metres short of the objective, the figure froze as the guard suddenly stiffened, as if alerted by some sound or slight movement – or perhaps just an intuitive sense that all was not quite right. He turned and peered in the general direction of the table, not even registering the dark, unmoving shape a few metres from it.

Eventually satisfied that there was no danger, the sentry shook his head, stamped his feet, marched a few paces to the right then back to the left, then shifted his spear to his left hand and rubbed his tired eyes with his right. He was bored and tired and, he told himself, it was when you got that way that you started imagining things.

He yawned, then settled into a slump, his weight resting more on one foot than the other. He sniffed wryly. He'd never get away with that relaxed posture on daylight sentry duty. But it was after midnight now and the sergeant of the guard was unlikely to come and check on him in the next hour.

As the sentry relaxed again, the dark figure slid the last few metres to the shelter of the table. Rising slowly to a crouching position, the intruder studied the situation. The sentry, after his shuffling and stamping, had moved a few metres further away from the table, but not enough to cause a problem.