A man's daughter is kidnapped, and the kidnappers mistakenly call an old number reassigned to another man. When the latter tries to contact the father, the kidnappers panic, leading the man to impersonate the kidnapper and extort ransom money from his own family, keeping some for himself.
See the Man Run
A group of kidnappers mistakenly contact a struggling actor while making a ransom demand, and the actor seizes the opportunity to get in on the action and claim a share of the loot.