Kirsten wakes up after a stitch and the lab is empty. After searching, she finds Cameron passed out on the floor. She slaps him awake. The two have no idea what happened. They can't remember who the latest victim was and when Cameron calls the NSA for help, they tell him that Mother is watching out for them. He thinks it might be code for Maggie, but Kirsten wonders if it's her mother.
They go to Kirsten's house. Camille isn't there, but there's another hot coffee cup that burns Kirsten, just as one did in the lab. Cameron makes dinner. Kirsten asks him questions about his mother. He says they were distant and she chose her boyfriend Bill over him. He talks about doing puzzles. They try to sleep, but Kirsten is confused when Cameron knows things about her childhood she never told him. She sees a woman watching them through the window.
Back at the lab, they find puzzle pieces in the monitors. Kirsten finds one in Cameron's locker and begins to doubt whether she can trust him. They find a puzzle in the stitch tank that leads them to a house with a classic car in the garage. There's a rubix cube in the glove compartment. The car won't turn off and they're trapped in the garage. Once they manage to get out, they go back to Cameron's. He realizes the cube has been tampered with to make it impossible to solve.
At the lab, Kirsten realizes she's still in the stitch and Cameron isn't really there. They discover the case their working on centered on an autistic man with empathic abilities. Cameron gives Kirsten a gun and tells her to shoot him. Even though he's not real, she can't bring herself to hurt him. He says it's because she loves him. Then, he accidentally gets shot.
Alone, Kirsten begins putting the pieces together. She sees a glimpse of all the victims they've helped over the years. Ed is there and he gives her the final push. She figures out Bill killed Tom and bounces. Back at the lab, everyone is confused. She explains how the murder happened and why and Maggie sends Fisher to arrest Bill. Kirsten realizes how worried Cameron must have been since she was in the stitch for days. Confused, he tells her it's only been three seconds.
She tells him that was enough time. Then, she kisses him.