We watch a woman board a bus followed by a suspicious man. We find that he is just the leader of a flash mob that ensues on a local bus. The woman, Serena Dunbrooke, we watch board the bus is found dead. She has died due to anaphylactic shock because of a being injected with bee venom. Boss and coworker questioned.
Hank and Nick visit a bee specialist. The toxic is not synthetic. They do not know where the toxin is from. Flash mobbers are broke in for questioning. Doug, one of the last interviewees is questioned again. Nick asks to see the tweet that was sent asking people to show up for the flash mob and suddenly he gets defensive. When Nick reaches for the phone, Doug starts to shift into an insect life creature.
Nick and Hank visit an abandoned, paper mill. They witness 3 people talking before suddenly being attacked by a swarm of bees. The badly stung Hank is patched up by Juliette. When Nick visits the trailer he discovers a correlation between the “Hezenbeist” and the “Mellifers,” they are enemies. Monroe comes back the paper mill with Nick sniffing out a woman’s perfume. They follow the scent to Melissa Wincroft’s house; a large eerie mansion. They find an open door and enter. A dripping noise can be heard in the distance as they walk toward it. Upon locating a room they open the door only to find a beehive. The officers assume that Melissa took revenge on Serena due to a lawsuit.
Nick and Hank are lead to another death, another lawyer working with Serena on the lawsuit. Adalind Schade is the third lawyer and they are assigned to protect her. Nick marks her as the Hezenbiest who tried to kill Marie. When asked he denies recognizing her. After visiting the morgue he finds that both of the dead women have the mark of the Hezenbiest. Back at the station Nick shows some aggression toward Adalind, hinting at her attack on Marie. As he and Hank go to take a break Adalind informs Renard that she is remembered.
With Melissa still missing, Doug is brought back in for questioning. Nick leaves him with his confiscated phone hoping to trace it to Melissa. In an attempt to hide Adalind, Hank and Nick take up shop in a nearby hotel. Still visibly aggravated by Adalind Nick reveals that he knows what she is and what she tried to do. Melissa is seen in a car talking to the bee keeper, who is also a Mellfer. She releases a swarm to find Adalind. Nick goes to help Hank fight off the bees that have discovered their location, leaving Adalind alone. The swarm lets up and they go back to find Adalind missing.
Nick goes to the basement where he is face to face with Melissa. She assures him that she is his ally and that killing the Hezenbiest is best. Melissa attacks Adalind and a fight ensues. Nick is held off by the swarm. Hank arrives and tries to stop Melissa but she almost injects him with venom. Nick is forced shoot and kill Melissa but not before she gives him a warning.