A few of the images feature Mr. O'Quinn as "Arthur Manchester;" other pics feature the rest of the cast. The episode is called "The Price Of Greatness" and this is how TNT describes it:
The 2nd Mass meets new faces, while Tom comes across his former mentor and professor Arthur Manchester (guest star Terry O'Quinn). But it's difficult to know whom to trust. Maggie begins to realize that Pope may not be sticking with the group very long. Tector embraces his military past.