I think the most important theme In the book so far is flight, because it is where all the action is happening. This is where bigger takes flight and kills Mary then plots to get more money out of it then kills Bessie for the fear that she knows too much.
"He avoided the car line, turned down dark streets, walking more rapidly now." (pg. 221)
He took flight because he knew that he was going to get caught. So he when to streets that were dark with no one walking down them. Then when he got to Bessie's house he got her, and went to a empty building. I think he is dumb. he should have left right after he killed Mary so he would have a few days head start. he didn't though because he felt like he was unstoppable, and he was getting a rush from it.
"Jan came forward again and Bigger drew his gun" (pg. 172)
He has more confidence now that he thinks that he is on top of the world. Bigger doesnt care who he kills, even Jan, or Bessie. It is because he won't let anyone get in the way of him and his freedom.