Grey-Kent scheme
Can someone explain the scheme Grey and Kent cooked up, which was not revealed (partially) until near the end of the movie?
Originally, Grey told Kent to just go to the station and protect the cryptographer. Then late in the show Grey asks Kent on the phone if he had killed the girl yet. Why did Grey want Katherine dead? Grey was not part of the group that was planning to assassinate 15 CIA higher ups and send bad guys to attack the station and kill Katherine. (Indeed Grey was one of the 15 intended victims.)
In the hospital Grey says to Kent that Katherine has to die because "she knows too much," but that doesn't say much. What was it about Grey that Katherine "knew too much?"
All of this also raises the question of what Kent knew about this Grey/Kent scheme and when did Kent know it. At what point did Kent know that his mission from Grey was to kill Katherine?
Maybe I just missed something. Thanks for your help.