Who is Hitmen from The Husband and what is their importance?

Two of Campbell's hit men are ordered to take Mitch to the desert and kill him. They put Mitch in the trunk of a car to transport him to the desert, but they don't know that Mitch has a gun hidden on his ankle. When they open the trunk, Mitch pulls the gun and kills one, wounding the other. He then runs off into a culvert, hoping to draw out the second man and killing him. The second man, however, is more experienced and more aware of the landscape, which leads Mitch to go back to the car and hide in the trunk. When the hit man returns, Mitch fires through the trunk and mortally wounds the hit man.