She also warns you not to arouse suspicions with Adamus Phillida, an Imperial Guard Captain and sworn enemy of the Brotherhood and says you must do this killing in a secure indoor location with no witnesses to receive your bonus.
She suggests speaking to your fellow Brothers and Sisters for advice. She wants you to find and kill a High Elf named Faelian, somewhere in the Imperial City. The mini-quest 'My Brother's Keeper' instructs you to speak with Ocheeva to receive your next contract.