The mission's objective is to score 20 kills using MP7. The weapon's spray is not too wide, so you can easily shoot in longer bursts. However, the weapon tends to slightly travel down and to the right. Below, three interesting spots where you can set an ambush have been presented.
Right after the wave ends, it is a good idea to climb up the ladder onto the balcony, from where you can access the corridor shown in the above screenshot. From this position, you can clearly see the incoming enemies between the pillars. As soon as you spot an enemy, you can open fire, or back up a little and throw a flash bang grenade inside, which will make them easier to eliminate. If the opponents do not appear within 15-20 seconds, get out of there, because they will be probably coming from a different direction.
Close to the spot shown in the above screenshot, you can keep an eye on the whole map. The first passage is on the right, right behind the wall, marked as "A". The other one is in the direction in which the weapon is pointing. By turning left, you can keep an eye on the side passage.
In this position, you can feel a little bit safer because you are between two covers of bricks and the wall. Across, you can see a corridor that opponents may use. To your left, there is a corridor. By leaning right from behind the corner, you can keep an eye on yet another passage.