The Nissir gang was the baron Lutz's militia near the border of Geso. The gang, referred to as "the minions of the law" by the baron, was known for raping women and killing cattle which greatly contributed to the fear they inspired in Nilfgaardian citizens. As such, they were quite renowned. The leader of the gang was "Trust Me" Vercta. He met with his friend, Skomlik, the leader of the Trappers and together they coordinated their respective gangs' efforts.
|“||"They're guarding their womenfolk," laughed the man who had wished ill on the cat. "The Nissirs are in the village! Did you hear what that yokel was saying. It's obvious they don't like them."
"And no wonder. Trust Me and his company never pass up on a chance. They'll get what's coming to them one day, those Lords Nissirs. The barons call them 'keepers of the peace', and that's what they're paid to do. To keep order and guard the roads. But try whipering 'Nissir' near a peasant's ear and you'll see. He'll shit his pants in fear. But they'll get their comeuppance. They'll slaughter one too many calf, rape one too many wench, and the peasants will tear them apart with their pitchforks.(...)"
— pg(s). 301-302, Time of Contempt (UK edition)
Baron Lutz of Tyffi had ordered the Nissir gang to capture the Rats, yet another gang. In particular, they captured Kayleigh and were in the process of bringing him back to Tyffi to be punished for robbing one of Lutz's administrators. Meanwhile, Ciri was captured by Trappers. Both gangs met up at the inn in Glyswen with their prisoners.
It was at the inn that Ciri helped Kayleigh escape by taking a knife from the Innkeeper and cutting his bonds. Vercta's group was slaughtered by Rats who also showed up to rescue Kayleigh.