The Buried Pyramid

Both a prequel and sequel to Imhotep, The Buried Pyramid begins as the Second Dynasty of ancient Egypt comes crashing to an end with the assassination of King Kha-Sekhemwy, the forced marriage of his daughter to the king's assassin, and the disappearance of Prince Djoser, rightful heir to the throne.  

The second half of the novel picks up the story 30 years later as Imhotep forces his way through a time portal in a desperate attempt to save his daughter's life. Encountering a mysterious doctor in modern Egypt, Imhotep flees back to the ancient world only to find he has triggered a series of tragedies that will change the face of the Two Lands and lead to his living entombment.