Patterson and her puzzle-expert boyfriend, David, decode a tattoo clue that sends the team to the Centers for Disease Control (CDC). While at the CDC, the team discovers a hidden message on Jane's body that uncovers a plot that could have catastrophic global consequences. Meanwhile, Jane and Weller grow closer.

In order to capture a dangerous international criminal, Jane and Weller are forced to collaborate with the only person he will meet: their former target, Rich DotCom. Jane must decide whether to risk hurting Weller by executing a morally questionable order from Oscar.