The Prisoner is the entry to the Path of the Captive, and it is built around the concept that defines the entire branch: shackles.
The body is strong, the senses are sharp; the canon notes that the Otherworldly of this step often have a sedate appearance and a mad heart within;
Shackledness — prisoners are not only those locked in a jail, but also those whose spirituality and desires are constrained by reason, the body, and the world itself;
Knowledge of the criminal craft — the bearer receives a multitude of criminal skills.
The second point is the key to the whole path. Shackles here are not a punishment, but a source of power: the stronger desires are suppressed, the greater their pressure, and the Path of the Captive is built on holding that pressure and turning it to one's own benefit.
The method of action says this directly: suppress desires and show restraint. The step requires not action, but self-restraint, and it is from this that everything further grows — up to madness, lycanthropy, and curses.
The formula corresponds: the Stone of Silence, the blood source of the mimic man, dirty water, and cedar essential oil.