This was just a warehouse before the apocalypse.
Inside an Atlanta warehouse, Rick plans an attack on the hospital. Tyreese suggests an alternate plan: kidnap two of Dawn's officers and arrange a prisoner exchange. Rick is skeptical that the plan will work, but agrees to it after Daryl lends it his support.
Rick's group brings the captured officers to the warehouse. Shepherd explains that their hostage plan won't work because Dawn does not consider them valuable on account of their ongoing plot to overthrow her. Lamson, however, assures Rick the trade will work if they talk to Dawn in the correct manner. "Let me help you," he offers, claiming kinship with Dawn.
At the warehouse, Lamson counsels Rick on negotiating with Dawn. He explains that Dawn will initially balk at the hostage deal, but will ultimately agree. Rick thanks Lamson and offers him water.
As Sasha guards Lamson, he describes seeing a former colleague-turned-walker melted into the asphalt outside. Sympathetic, Sasha offers to shoot the walker to end its misery.
Back at the warehouse, Lamson directs Sasha to a window and tells her where to aim her gun. As she's staring through the scope, Lamson slams Sasha's head into the window. With Sasha now on the ground, bleeding and unconscious, Lamson makes his escape.
Rick returns to the old building, and tells the group that he had to kill Bob. The two other officers explain that if Dawn knows how he was killed, she will take it personally. Thus, they agree to tell Dawn that Bob was taken by walkers. This will allow Rick to get in with minimal violence.