Susan's family had been part of the Resistance. Nothing quite like the Fifth Column, but what they'd done was help to shelter the non-combatants. It wasn't glamorous, but it did help to protect those who were too afraid to fight, or were unable to do so. The Strongstripes, as there were known by their Were-name, had a lot of Slaves and Pets, in so far as the Masters were concerned.
Sometimes though, a message needed to be sent to the Resistance, so that they could get rid of a Secret Claw member, or a Fanatic. Especially those who proved to be too much trouble to have in the area. Sometimes accidents needed to be arranged.