“As an empty squares board,” he murmured, standing over the stricken guard, “and all according to plan. What do we most despise, after all?”

“Mustard?”

“And?”

“Accidents.”

“Correct. There are no such things as happy ones. Get his boots.”

With considerable effort they manoeuvred him down the hallway to his desk and into his chair. His head flopped back and he began to snore, long moustache fluttering gently around his lips.

“Ahhhhh, he sleeps like a babe. Props, if you please.”

Day handed him an empty spirits bottle and Morveer placed it carefully on the tiles beside the guard’s boot. She passed him a half-full bottle, and he removed the stopper and sloshed a generous measure down the front of the guard’s studded leather jerkin. Then he placed it carefully on its side by his dangling fingers, spirits leaking out across the tiles in an acrid puddle.

Morveer stepped back and framed the scene with his hands. “The tableau… is prepared. What employer does not suspect his nightwatchman of partaking, against his express instructions, of a measure or two after dark? Observe the slack features, the reek of strong spirits, the loud snoring. Ample grounds, upon his discovery at dawn, for his immediate dismissal. He will protest his innocence, but in the total absence of any evidence”—he rummaged through the guard’s hair with his gloved fingers and plucked the spent needle from his scalp—“no further suspicions will be aroused. All perfectly as normal. Except it will not be normal, will it? Oh no. The silent halls of the Westport office… of the Banking House of Valint and Balk… will conceal a deadly secret.” He blew out the flame of the guard’s lantern, sinking them into deeper darkness. “This way, Day, and do not dither.”

They crept together down the hallway, a pair of silent shadows, and stopped beside the heavy door to Mauthis’ office. Day’s picks gleamed as she bent down to work the lock. It only took a moment for her to turn the tumblers with a meaty clatter, and the door swung silently open.

“Poor locks for a bank,” as she slid her picks away.

“They put the good locks where the money is.”

“And we’re not here to steal.”

“Oh no, no, we are rare thieves indeed. We leave gifts behind us.” He padded around Mauthis’ monstrous desk and swung the heavy ledger open, taking care not to move it so much as a hair from its position. “The solution, if you please.”

She handed him the jar, full almost to the brim with thin paste, and he carefully twisted the cork out with a gentle thwop. He used a fine paintbrush for the application. The very tool for an artist of his incalculable talents. The pages crackled as he turned them, giving a flick of the brush to the corners of each and every one.

“You see, Day? Swift, smooth and precise, but with every care. With every care, most of all. What kills most practitioners of our profession?”