My ex took our son without my consent. There are currently no orders in place. What do i do?

I would call the police and tell them the history of abuse and violence, and that your scared he may hurt your son they might help then. or just go and get your son when he dont know because you also have the rights and when you get in court tell them you were both happy with the custody and all of a sudden he wasn't and it would more mentally better for your son to live with you then his father.