be let off the hook

To be pardoned, vindicated, released, or allowed to avoid blame, responsibility, obligation, or difficulty. At first, Sam was suspected of stealing money from the safe, but he was let off the hook after security camera footage showed it was someone else. A: "I thought you had that big work event tonight." B: "No, it got canceled, so I've been let off the hook." I did get pulled over, but I was let off the hook with a warning, thank goodness.

off the hook, to get/to be let

To escape from some difficulty. The analogy is to throwing a fish one has caught back into the water, saving its life. The term on the hook goes back to the seventeenth century; the current cliché dates only from the mid-1800s. Anthony Trollope used it (The Small House at Allington, 1864): “Poor Caudle . . . he’s hooked, and he’ll never get himself off the hook again.”