A security locking system for trailers that features an interior locking bar that is controlled from the outside. The locking bar is traversed in a linear motion parallel to the door by means of a toggle mechanism. The bar is guided into the locking mechanism by two guides mounted to the inside of the trailer door. The toggle mechanism is turned using a common trailer latch that also locks by use of a key. Alternatively the latch could be modified to lock or unlock by means of a remote. Once the latch is turned all the way (90 degrees), it will raise the locking bar into the upper secure bracket. The lower part of the locking bar will be lowered into the lock housing which is hidden just under the trailer floor; it will then be in position in the locking mechanism for the key pin to be inserted and then locked. The locking mechanism can also be modified to be controlled by means of a remote.