A must-have book for someone with a family member who has OCD. The first section is educational about what OCD actually is. The second part give practical advice for how to deal with a family member's compulsions and each chapter deals with checking, avoiding, seeking reassurances, washing and cleaning, and mental rituals. He also has a chapter specifically about family dynamics and how to handle if your child, parent, or spouse has OCD (because your role will change to some degree depending on your relationship). He also is very explicit about what your role is . . . and isn't.
Also, at the end he gives helpful information about how to locate resources as well as questions to ask therapists. As I found out through trial and error, all therapists are not created equal and it's important not to waste time and money onboarding with someone who's not a right fit. Asking questions like "Do you specialize in CBT? How much of your practice focuses on OCD?" and "Do you use exposure with response prevention (ERP)?" are essential in finding the person who will help in the fight against OCD. (A therapist who specializes in anxiety, for instance, can actually hurt, not help, but that's an easy mistake as OCD produces anxiety.)