Red informs the team that "The Alchemist" (guest star Ryan O'Nan), a man who relies upon science to transform a person's DNA and their appearance into someone else's, has been contracted to protect a well-known mob informant and his wife. As the team goes undercover to catch him, Elizabeth finds herself on the hunt for an unlikely couple. Meanwhile Elizabeth and Tom find themselves at another bump in their relationship and Ressler debates whether or not he should give his ex-fiancee his blessing. Meanwhile, Red continued conducting more investigations of his own and discovers the identity of the FBI double agent: Meera. He later pays Meera a visit at her house with a loaded gun to interrogate her. Also, Lucy Brooks, the woman Red was looking for in ViCAP, is shown with files about Liz and Tom, and she infiltrates the Keen's baby shower party, introducing herself as "Jolene Parker," a substitute teacher. She flirts with Tom and in the end, they visit an art exhibit together because Elizabeth is late from work.