Abstract: A locking mechanism for securing the upper swinging edge corner of a door to the adjacent door jamb joint comprises a housing holding a flat sliding latch mounted at an angle on the door corner. The latch slides toward and past the door corner and has converging leading edges normal to each other such that they meet at an apex. One leading edge is parallel with the top of the door and the other leading edge is parallel with the swinging side of the door. Receiver means are contained in the corner of the door jamb having receiving channels in alignment with the leading edges of the latch such that when the latch is pushed forward in the housing, the leading edges of the latch are received into and held in the receiving channels. Forces exerted against the locking mechanism when the latch is secured in the receiving channels are distributed along both the top and side edges of the door and door jamb instead of at a single pressure point.