Tag should be used if the main protagonist either is being blackmailed or is the one doing the blackmailing.

Blackmailing the act of getting money from people or forcing them to do something by threatening to tell a secret of theirs or to harm them.
Seo Tae Hyuk, jailed after being falsely accused. He will be executed without being able to prove his innocence. When he opens his eyes, it’s 15 years in the past?