He and his troops found James Edward Allen's expedition just after the murder of Major Raykal. He had everyone who was carrying a weapon shot. He killed Allen when the ex-astronaut tried to leave with the expedition's notes. He allowed the prisoners to bury the dead, then Jason Kane bribed one of the guards to let them escape.
Whilst giving chase, Tammuz and his troops ran into those of Colonel Samran. They killed all the soldiers except for Tammuz, and caught his prisoners as well. He interrogated them about their expedition, which he believed was really searching for uranium. He had them dig up the cube that was part of the Genesis of Cthalctose transmat system, but could not open it. When he heard that Iranian reinforcements were heading for them, he tied up everyone and planted explosives so no one else could gain the technology.
Bernice Summerfield was able to activate the transmat before they were blown up, which sent them to the Moon in the Sea of Tranquility. Everyone except Benny and Tammuz died from explosive decompression, who were rescued by people from Tranquillity Base. Tammuz believed he was still on Earth, and the base was a secret American military installation in the area of his homeland. He forced a technician to activate the Genesis of Cthalctose, sending Liz Shaw and Agent Yellow to Earth. Later, when the singularities powering the Cthalctose terraforming platform were freed to deactivate the control systems, Tammuz tried to escape in a lunar rover. He was sucked into one of the singularities, killing him. (PROSE: Eternity Weeps)