Downfall

The 'pressure' part is the human presure of being hit by a terrorist attack. Nothing larger there :)

How about this:

Caught in the middle of large scale terrorist attack an unlikely group of co-workers must work together to stay alive and get out of their collapsing building.
But who can you really trust when everyone is under extreme pressure?

You have a lot of the meat in that first line and lose steam with the second line. Not knowing your story I'm guessing the element of "pressure" is something more mysterious or wider in scope than simply a life or death situation, maybe distilling it down into something like:

In the aftermath of a terrorist bombing, a group of strangers trapped in a collapsing building begin to suspect one of their fellow survivors may be responsible for attack.