Having distracted the zombies enough to take only one down felt a lot like bad luck. How many Hail Mary's had he prayed in his confession? Hell, when even was his last confession? 'Forgive me Father for I have sinned. I've killed two diseased human monsters and one of them I used hand out soup with on Wednesday nights.' Yeah...
In that moment, before he could face the next lumbering zombie, a woman appeared from a window behind him, clearing out broken glass with her baseball bat. Not only that, but she seemed completely capable, dispatching a crawling biter with a single wicked hit from her bat. When he heard her call, Keller decided her plan was leagues better than facing another two or three zombies in this alley.
Then, as if on queue, the Big Man upstairs needed to keep Isaac in line; inches away from him, some sort of hulking mass of plastic and metal came crashing down, sending pieces flying in all directions. Isaac brought his injured arm up in just enough time to deflect a small amount of debris that came at him. Looking up, he saw a man's head sticking out over the edge of the roof ledge.
Rather than linger on the thought of why someone had tried to kill him, all while he was in the middle of a throng of zombies... The benefit of the doubt would be that maybe he was trying to help? Isaac would go with that for now. After the sound of that huge crash and clatter, he was sure many more hungry mouths would show up in the alley at any moment. Getting to his feet again, Isaac turned toward the woman and made his way in her direction, back through the way she had came.