Abstract: A lock for releasably holding closed a fixed structure like a house or building a hingedly mounted closing element like a window guard, gate or the like characterized by a lock bar for being locked in the closed position from a lock housing that is connectable with the fixed structure and has a latch that is inaccessible by an outsider but that will snap into position about the lock bar to hold it trapped yet releases when pushed from inside the building, the push operating a bell crank that effects the release. The latch includes a trapped, slidable release bar biased to snap into engagement but pushable by the bell crank to release engagement. Specific preferred embodiments are also disclosed.