The Mummy ending explained: Katie's abduction and the Nasmaranian's transfer

Katie Cannon was found alive after an eight-year abduction, but her return brought an ancient evil into her family's home. The evil, known as the Nasmaranian, possessed Katie after she was used as a replacement host in a ritual to contain it. The creature feeds on family discord and was transferred to her father to save her. The family now holds the Nasmaranian within Charlie, contained in a chest, while plotting to transfer it to Katie's abductor, the Magician.