Stefan Skellen's gang consisted of various mercenaries, thieves, and bandits from across the region. While the purpose was for Stefan Skellen to hunt down and kill Ciri, this wasn't relayed to most of the gang members, only that they were looking for a certain girl.
Members of the gang were recruited by Dacre Silifant, Ola Harsheim and Bert Brigden and they were then brought on the 14 September at Rocayne, where Stefan Skellen was waiting. Unbeknownst to Skellen, there were two traitors among his group: Neratin Ceka, having been planted by Skellen's boss Vattier de Rideaux, and Jediah Mekesser, who was a spy for the sorceress Assire var Anahid.
The first task of the gang was to investigate on what Leo Bonhart did after he slaughtered the Rats with the exception of Falka in Jealousy: Nycklar, a young boy hired to Bonhart to deliver some letter, was captured from Malhoun and was brought to Rocayne, where Stefan Skellen interrogated him; it turned out that the letters Nyclar delivered were addressed to Esterhazy of Fano and to Dominik Bombastus Houvenaghel of Claremont.
On 16 September Boreas Mun, Neratin Ceka, Chloe Stitz, Andres Vierny, Cyprian Fripp, Dede Vargas and Joanna Selborne went to Fano and interrogated Esterhazy, the local weaponsmith. Esterhazy told them that Bonhart and Ciri were here four days before and that Bonhart bought a sword for Ciri.
After the incident in Unicorn which left several members dead, Skellen then had them search the nearby forests for the escaped Ciri, but with no luck. With winter coming, he decided to have them split into groups and stay in various villages in the area, believing Ciri, to escape the cold, would visit one of them soon, not realizing she was safe and warm in an isolated hut in the swamps.
One of the groups was staying in Dun Dare and when Ciri heard about them attacking and killing several of the villagers, took it upon herself to be the bearer of justice, killing the 4 members. However, this put Skellen's gang on her trail, now with Rience and Leo Bonhart among the ranks. The group chased her all the way to Mil Trachta, as the mythical Tor Zireael was there.
Just as the group reached the frozen Tarn Mira lake, several members made it clear they weren't going to continue, having had nightmares of drowning in a frozen lake, and left, reducing the gang down to about 10 people. With the ice being too thin to support horses, the rest set out on foot across the lake, believing they'd soon catch Ciri, as her tracks were very fresh. Suddenly Bonhart changed plans and went back to get his horse, but the rest continued on. However, they couldn't see anything in the fog and Ciri's tracks suddenly stopped. Too late, they realized she had skates and was literally skating circles around them, striking decisively. Rience, panicking, tried to break the ice to stop Ciri's momentum, but instead broke it where the group was standing, sending the few survivors into the water. Skellen and Boreas managed to get out, but Ciri cut off Rience's fingers and he drowned in the freezing waters.
Sometime later, Bonhart, Skellen, and Boreas made it to Vilgefortz's hideout, Stygga Castle, and Skellen boosted up his gang with more mercenaries. However, as soon as Geralt's company assaulted the castle, many of them ran off. Boreas, the last known member of the original gang that was still around, actually let the company know which way to go before he too took off. Bonhart was later slain by Ciri and Skellen tried to make one final stand in the only stairwell out of the castle. However, every mercenary he sent up was struck down by Ciri and Geralt. Before the two could deal with Skellen though, the Nilfgaardian Army, with Emperor Emhyr in toll, appeared and arrested Skellen and the rest for treason.