Frost And Iron. Daughters of Iron, #4

A frozen fortress. A lethal secret. A ghost from the past. The Daughters of Iron are elite mercenaries for hire, and their latest contract takes them into the heart of a Siberian black site that officially doesn't exist. Ava, Maggie, and Jess are tasked with Operation Frost Line: extracting a high-value "cognitive specialist" from a facility built on Soviet brutalism and secrets. The payoff is enormous, but the mission requires a high-altitude jump into a sub-zero whiteout where the cold kills faster than the guards.
When the team breaches the concrete tomb, Ava realises the asset isn't just a target-he's a figure from a past she thought was dead and buried. Now, hunted by "human-supervised" AI and trapped deep beneath the ice, the Daughters of Iron must turn a tactical surrender into a violent breakout. In this wasteland of frost and iron, the only way out is to burn it all down.