Reese is getting buried under the paperwork in his undercover identity as Fusco's partner, and Shaw is adjusting to her new undercover identity as a street level criminal. As such, Reese foists off dealing with the latest number to Finch, who still is hesitant to continue such work. Finch decides at least to start the process if only because the number is akin to someone like him. She is college sophomore Claire Mahoney, a seemingly brilliant young woman with an analytical mind. However, her life seems to have fallen off the rails in the past year, ditching her college studies and having recently purchased a firearm. As Finch tails her, he believes that she is involved in some deadly code breaking game/puzzle, the puzzle which always involves the figure of a nautilus. In addition to tailing her, Finch also tries to figure out who set up the puzzle and what its purpose is. Eventually Reese, Shaw, Root, Fusco and Bear get involved in helping Finch to varying degrees. What they collectively discover is that what happens to Claire has an indirect bearing on their own survival.