The invention pertains to a lock (10) for locking a mobile structure to and unlocking it from a fixed structure (11) on a vehicle, one of the two structures containing a first keeper (14), the other structure containing a second pin (16) around which the lock can pivot, the lock comprising: A lock strut (19) containing a hook (33) able to latch onto the keeper; A handle (17) with a third pin (28) around which the lock strut can be guided in its rotation, the second pin (16) being located toward the handle (17) in relation to a plane (29) formed between the first keeper (14) and the third pin; and a fourth pin (46), located between the handle and a first side (35) of the lock strut; A first connecting rod (45) linking the third pin (28) to the fourth pin (46); A second connecting rod (48) linking the fourth pin (46) to the second pin (16), and a fifth pin (49) located against a second side (50) of the lock strut opposite the first side (35).