He had been trained in the ways of the ninja. He spent most of his life, dispensing of the rich and powerful for the rich and powerful. He'd come over to this strange land on a boat five years ago. He had taken commissions in Quirm, Sto lat, Genua but until now never in Ankh-Morpork. Though he thought their assassins arrogant fools he knew about the power they wielded.
That was going to change soon, he had been given a commission to kill the city's ruler. It had been laughingly easy to get through the security of the palace with his stealth and his skills. He watched and waited until well after midnight.
He wondered why everyone was frightened of this Lord Vetinari, true the man had been trained as assassin but hadn't been active as one in decades, he had bad leg, he was over forty.
The ninja entered silently through a window, the Patrican's back was turned he seated doing some paper work. The ninja was poised ready to strike. Then the patrician spun around. The ninja caught a glimpse of something metal in the man's hand, he tried to dodge, but the strike was sudden, so fast he hardly had time to blink. Yet, there pain, there the knife blade imbedded deep in his chest and the blood was pouring out, so much of it. As he sunk to his knees dying, he saw the tall, pale man standing over him, watching him with a look of mild interest.
When he was sure the ninja was dead. Lord Vetinari, picked up his speaking tube.

"Drumknott, there is a corpse I need disposed of. Also tell the housekeeper to change the carpet. And I'd like to have a talk with the head of palace guard. This is the sixth ninja I've personally had to deal with this year alone."