Colonel Regan should have been Isabel's salvation. Seriously—she came to him with information that Lockton and his Loyalist cronies wanted to kill George Washington. Information that valuable should have been worth first-class seating on a cruise ship for Isabel and Ruth. Instead, though, Regan ends up violating his promise to Isabel that in exchange for her intelligence data, he would "personally look into [her] case" (16.66). Boo and hiss.
At first, Regan appears to respect Isabel as a source of valuable information about his enemy—he even gives her the code word to the American camp. In the end, though, the rules of society prevail over any desire he may have to help Isabel.
When she runs to the camp for help after Madam sells Ruth, his sentries tell her that since she is the Locktons' property, it's not his place to help her. "The law binds my hands and my actions," he says, without making eye contact with Isabel. "Even during times of war, we must follow the rules of propriety and civilization" (21.112). Ugh.
Propriety? Civilization? What a jerk—like ignoring a girl who took a major risk to help him is proper or civilized. Regan is yet another example of a supporter of liberty and independence who seems blind to the hypocrisy of slavery.