hold somebody to ransom
hold (one) to ransom
To demand something or some action from someone by threatening them with a harmful consequence if they do not comply. Threatening us with a fine if we don't participate in the survey is a bit like holding us to ransom, isn't it?
hold somebody to ˈransom
1 hold somebody as a prisoner until money has been paid for their release: The kidnappers held the little girl to ransom for more than eight hours.
2 try to force somebody to do what you want by using threats: The government said that the workers were holding the country to ransom by demanding a ten per cent pay rise.