Dr. Lysander was one of England's most trusted and experienced doctors, and the inventor of the Slating procedure. She was also a mentor to Kyla Davis after her Slating, and a friend of Samantha Gregory.
Dr. Lysander was told by the Lorders that Kyla was dead, and believed it until MIA arranged for Kyla to visit her. Kyla snuck in to her hotel room, and was able to briefly talk. She told her about the pictures of the Slated children in the orphanage, and other odd actions by the Lorders. Dr. Lysander states that she doesn't know anything more about Kyla's DNA other than it was classified, but does say that there was a report where the hospital board recommended termination of Kyla's Slating and she overruled. She suspects it was a Lorder as she does not have the power to overrule the hospital board. Kyla rushes out apologizing that they couldn't talk more, and accidentally cuts herself leaving a little blood behind, which proved critical later in the book.
As Nico is about to shoot Kyla, Agent Coulson, the Prime Minister's Head of Security, shoots Nico before he can kill her. Kyla finds that Dr. Lysander and the Prime Minister are with him, and they take Astrid Connor away for her actions. She makes sure all injuries are treated and makes the ambulance take away Ben, Skye, and Tori's body. After they are taken away along with Astrid and her Lorders, Dr. Lysander explains that she swabbed the blood that Kyla left behind in the hotel room for her DNA, and found it was the same as the Prime Minister's daughter. She alerted the Prime Minister and thanks to Coulson's sources, arrived on time. The Prime Minister does the rest of the explaining and officially resigns.
Later, Dr. Lysander removes Kyla's brain chip that can cause her pain, along with the Levos and brain chips of other Slateds. She also returns Ben's memories while Kyla is present, and makes sure he can see them. When Ben morphs into his old self, Nate, and runs away, it is clear that Dr. Lysander never trusted him once he was Slated for the second time.
Dr. Lysanders future is unknown, though it is assumed she continues her career as a doctor and reasearcher, although she no longer performs Slating surgery as it was outlawed.