Unfortunately for the conspirator who planned the assassination, his own daughter - Gilda - trots on through and is slain.  
The curse of Count Monterone resonates throughout this opera, both opening and closing the action.  In between, the title character pays Sparafucile to kill the Duke of Mantua, but the assassin instead decides to kill the first person that walks in the door.  Unfortunately for the conspirator who planned the assassination, his own daughter - Gilda - trots on through and is slain.  FTP, name her father, a court jester, and you've named this Giuseppe Verdi classic.
The curse of Count Monterone resonates throughout this opera, both opening and closing the action.  
Rigoletto