A cover is manually releasably locked to the base of a storage container for protecting the contents of the container from accidentally or inadvertently opening even on dropping. A forked member is mounted on the cover having tongues with eyelets extending downwardly therefrom which fit into a latch housing in the base which contains slots for receiving the eyelet tongues. A slidable actuator is movably mounted in the latch housing which housing includes a first and second latch which are adapted to engage the eyelets of the tongues of the stem when the cover is closed on the container. Spring means are provided for urging the first and second latches into the eyelets which are released by a multiple-step technique in which the actuator is moved in a first direction for removing the first latch from one of the eyelets and then moved in a second opposite direction which removes the second latch from the other eyelet, and by gently, continuously and evenly lifting the cover upwardly while the latches are being released in sequence. If the actuator is moved too far in the second direction, a third latch engages for preventing opening. If the continuous lifting force on the cover is too strong the lock cannot be opened. If the gentle continuous lifting force is uneven or interrupted one of the latches becomes engaged by the spring means for preventing opening, thereby preventing the accidental or inexperienced, unauthorized opening of the container.