In episode 4.09 I Know What Du Did Last Summer, Castiel returns with Uriel seeking Anna Milton, a girl with a special ability to "hear" all the communications between the angels. They plan to kill the girl, though for reasons beyond the brothers' initial understanding. It is later revealed in Heaven and Hell that Anna was once an angel, and that she outranked Castiel much in the same way he is above Uriel. Thus, not only could she be interrogated Von Hell for what she can hear, but also of what she already knows of Heaven. Though the group managed to escape him and Uriel, the two Engel eventually track them down with information from a reluctant Dean. They had threatened to send him back to Hell, and although he still resisted, he eventually relented when they threatened to kill Sam as well. Castiel chose not to deliver this message, as according to Uriel, he liked Dean too much.