It started with wizards.
Vimes hated wizards.
Oh, he had nothing against them as people, which is to say he had no special reason to distrust them more than he distrusted everyone else.
But, ye gods, every case involving wizards was a nightmare.
One moment they were yelling about unlicensed thieves, and the next their latest godsdamned contraption was glowing in colors he hadn't known existed.
And then he woke up, collapsed on the ground.
Vimes was instantly comforted by the sight of a dark, grimy, thoroughly criminal-looking street.
Until he got up and felt the cobblestones under his boots.
They felt wrong.
Those weren't Ankh-Morpork cobblestones.
He looked up.
Those were definitely not Morporkian buildings. And what the hell were all those twisting spires? Even Klatchians didn't make buildings as bizarre as that.
After a moment, he slowly drew his sword.
And of course, whenever there is a lost traveller whose appearance will make anyone ask him all sorts of uncomfortable questions, a policeman will be instantly drawn to wherever he is. This is basic narrativium, and while London had no such element, Sam Vimes had a way of bringing an quintessential Morporkianness wherever he went.
Therefore, a Constable came stomping by, saw Vimes, checked his vision, saw that there was indeed a man dressed like an Roman soldier crossed with a drunkard on the bad side of Spite*, and took out his trucheon.
"Alright, who are you, then?" the Constable demanded.
He did not get a chance to repeat the question, given that his neck now had considerably less blood, and considerably more knife, than was healthy.
The half-dozen passersby, convincing Vimes that whatever city this was had a reassuring similarity to Ankh-Morpork, began to Innocently Keep Walking Without Seeing Anything Unusual***.
Vimes, who was doing no such thing, looked for where an assassin**** would hide.
Someone was standing in the shadows of a nearby alleyway. It was a talent to that someone's skill, that, had Sam not had a particular advantage at seeing in the dark, she really would have been difficult to spot.
She looked directly at him, and nodded in the direction of the alleyway.
Well, Vimes thought, it's not as if he had anywhere better to be.
* Not that Spite had a good** side, per say, but it was a question of degree.
** Here good really means what a policeman would call good. Union-controlled Spite was fairly peaceful and had very little theft, due to the combination of good wages ensuring that no one needed to steal and union men being very unhappy with the idea of anyone stealing from a Fellow Worker. However, it did have a lot of smugglers, due to no one there being very keen on being taxed just to line Mr. Fires' already enormous pockets. More importantly, it also had a lot of well-armed poor people who didn't like cops, and therefore was The Worst Side Of Spite.
*** This wasn't, strictly speaking, inaccurate. Dead constables really weren't that unusual in London.
**** This was not Ankh-Morpork, and therefore the killer was not an Assassin.