Fig.: to escape from a difficult situation, with no collateral blame or trouble

The file of an important client of mine was missing, but my boss got me off the hook by saying that he took it to look at it

Il fascicolo di un mio importante cliente era scomparso, ma il mio capo mi ha cavato dagli impicci dicendo che l'aveva preso lui per dargli un'occhiata

The flight was in overbooking, so the airline offered a new ticket and a money reward to anyone who would volunteer to get off the plane and let them off the hook

Il volo era in overbooking, così la compagnia aerea, per togliersi dai pasticci, ha offerto un nuovo biglietto e una ricompensa in denaro ai volontari disposti a rinunciare al volo

He was a suspect, but then he managed to give a bulletproof alibi and was off the hook

Era uno dei sospettati, ma è riuscito a fornire un alibi di ferro e si è tirato fuori dai guai

This phrase refers to the fish that manages to free itself from the hook of a fishing pole and get away