king's ransom
A very large sum of money.
"But to yonder pavilion . . . the moon is glimmering on the gilded ball which crowns its roof, and which is worth a king's ransom."
VERB + RANSOM
hold sb for/to, kidnap sb for
The rebels held the politician for ransom until the government agreed to their demands.
demand | pay
RANSOM + NOUN
demand, note | money, payment
PREP
for ~
The kidnappers demanded a million dollars for ransom before releasing the businessman.