Contains spoilers for this episode and earlier episodes.
An attempted museum robbery ends with a guard shooting two men disguised as police. Torres had vetted the museum's staff, bringing the failed security check back to the consultancy. At the hospital, Lightman meets Naomi Russell and notices a man watching her. Naomi describes him as a former lover, Jack, who will not leave her alone. Cal takes her home after another encounter, allowing a flirtation to pull him further into her account.
Gillian and the team discover that the museum's painters were outside the original checks. One, Al Larson, admits knowing Naomi and the dead would-be robbers. Jack works in customs, giving him access useful for moving stolen art. Lightman realises Naomi has been playing him, but invites her to the exhibition opening. There, a guest is drugged and an emerald disappears while a white-haired man leaves in a taxi.
Naomi says the emerald is being returned to the temple from which it was taken, presenting her role as an attempt to correct an old theft. She used Cal to reach the reception while her partner carried out the operation. Lightman walks away from her invitation to dinner, then tells Gillian that he anticipated the theft and had the real emerald replaced with a fake. Naomi escaped with the substitute, but his refusal to share the plan leaves Gillian angry about being excluded again.