This story happens in the nearest future. Some terrorist organization sponsored by another organization develops a system of portals that allows you move almost any object anywhere in the world. This helped terrorists to move fighters right under the noses of the authorities. Besides fighters they use robots with the nuclear warheads, which create a "parallel organization". They have already set up this system under more than a dozen cities, but scientists have found portals that have "interchanged" points which do not work properly, and so there are places where the terrorists have to transfer their robots from one portal to another. Scientists are to figure out these places, and your goal is to establish defenses at these points and destroy all robots. Fortunately, they are highly combustible. The ultimate goal is to identify the enemy's headquarters, and destroy it.