Complex sentence: Waller then deploys the squad to extract a high-profile mark from Midway, however the squad is briefed and put under the impression that what is going on in the city is a terrorist attack.
Split into simpler sentences: Waller then deploys the squad to extract a high-profile mark from Midway. However, the squad is briefed and put under the impression that what is going on in the city is a terrorist attack.