A rim lock, particularly such a lock fitted subsequently to a door, window, shutter or the like, which includes a through-penetrating opening for accommodating a lock cylinder, wherein the multi-point lock includes a first bolt and at least one second bolt, and coupling means for connecting the bolts with a lock cylinder accommodated in said door opening, for simultaneous manoeuvring of the bolts in response to actuation of the lock cylinder. With the intention of facilitating fitting of the lock, the bolts (3, 4a, 4b) and the coupling (5a, 5b) are disposed in a cassette (1) and a lock cylinder having a cross-sectional shape for guiding or controlling the cassette during mounting projects through a cylinder opening in the cassette.