Pharaoh's Son - Diana Wilder M

The crash of Pharaoh's colossal statue into a throng of worshippers brings the festival of the good god Ptah of Memphis to a sudden, bloody end. Prince Khaemwaset, the High Priest, barely escapes with his life. He finds clues in the wreckage that show that the disaster was deliberately set. Now he is confronted with questions that grow more alarming with every answer he finds as the great temple of Ptah is rocked by a chilling series of murders. 

Increasingly entangled in clues that lead to even more mysteries, convinced that the gods themselves are taking a hand in the disaster, he appeals to Pharaoh for help and is sent a powerful ally in his eldest brother Hori, Egypt's Crown Prince, whose intelligence, courage and cunning are offset by a devastating bluntness. 

The brothers fight against time as they try to unravel the mystery, knowing that there is more at stake than treasure, and the forfeit is greater than a man's life:

Something great and terrible is stirring, something hidden deep within the temple, something they must find and bring into the light before those who walk in darkness take it and turn it to evil.