Exorcism
In Catholic Christianity, exorcisms are performed in the name of Jesus Christ. A distinction is made between a formal exorcism, which can only be conducted by a priest during a baptism or with the permission of a bishop, and "prayers of deliverance" which can be said by anyone.
The Catholic rite for a formal exorcism, called a "Major Exorcism", is given in Section 11 of the Rituale Romanum. The Ritual lists guidelines for conducting an exorcism, and for determining when a formal exorcism is required. Priests are instructed to carefully determine that the nature of the affliction is not actually a psychological or physical illness before proceeding.
Alien Exorcism
Dr. Davide Piso is a courageous scientist who has been studying thousands of cases involving alien abductions with the aid of hypnosis. When the scientist decides to help Saturnia, a seductive teenager that believes herself to be an alien abductee and shows a clear attraction for him, he faces an insurmountable problem: once hypnotised, Saturnia cannot leave the trance condition anymore, hence giving manifestation to Hexabor of Ur, an alien entity coming from Mesopotamian ages. Hexabor considers himself a demi-god and wants to exploit a special human energy: the soul.