“Empire of Death” is the typical Russell T. Davies series finale: It’s bombastic, dense and totally uninterested in resolving its own story. The episode bounces around for the requisite amount of time before leaping to its climax with an arresting visual of little substance. Because what Davies is” the Doctor and Mel are face to face with Sutekh’s minion . Sutekh begins spraying its dust of death, a cloud of dust that turns whoever it touches into a pile of dust themselves.
Once the information is on screen, they’re all pulled back to UNIT HQ in 2024 by Sutekh who is similarly curious. Sutekh uses his power to pull the Doctor to the floor, threatening his life, unless Ruby shares the information held on the gizmo she’s holding. But as she gets close to the pooch, she smashes the screen with the data on it and clips a piece of smart rope to Sutekh’s collar to ensnare him.
Back at UNIT HQ, with everyone revived and eating pizza, they’re able to track down Ruby’s mother. She got pregnant at 15 and gave her daughter up to avoid the reprisals from some sinister stepfather who may have harmed the child. But she never sought to track down her daughter afterward, and didn’t even tell the father of the child that she’d had a baby. As for why Sutekh was interested in Ruby’s mother, the Doctor says it’s because people had invested time and emotion into her.