At nearly 18, Andy was almost free of her outwardly honest and eminently suitable guardian.
Andy knew him better. Her brother Martin was a crook, but proving it? She didn't dare.
After a series of events put her in trouble, Andy runs away, but Martin was not about to let her out of his control. He wanted her to have no reputation left, and if she wouldn't do as he wanted, locked up rather than free.
He needed money. Needed her inheritance. Once he had that, he wouldn't care what happened to her.
Would not caring about Martin make Andy safer when his enemies find her?