Lauren and Bo have been spending a lot of time together so that Bo can learn to control her feeding urges, but Lauren has to work hard to tamp down her romantic feelings for Bo. She invites Bo and Kenzi to come on a house call with her, but Kenzi's ravenous appetite keeps her in the kitchen and out of the sick room.
They visit a woman named Halima, a Fae who eats the corpses of humans. She's bleeding from her eyes and internally, and no one has any idea what's causing it. Halima doubts it was related to her food, although the foot soup she made did give her indigestion. Lauren and Bo go to collect Kenzi moments too late - she's eaten the soup, and before long, she falls ill. Bo will stop at nothing to save her.
The foot came from a man who had a shady relationship to a company called Behren Chemicals. Lauren disguises herself as a visiting consultant while Bo uses her natural and supernatural powers of seduction to get a job as an assistant to one of Behren's officers, and the two look for anything amiss at the company. Lauren discovers something odd in Sector 6, so she and Bo devise a plan: Lauren will create a diversion while Bo uses the keys she pilfered from her new boss to gain access to the Sector.
Dyson spends as much time at Kenzi's bedside at Light Fae headquarters as he can, but when the mission to crack Behren Chemicals calls him away, Kenzi takes the opportunity to escape from the watchful eyes of those who hold humans in such high disdain. Dyson finds out and tracks her scent - to a graveyard. He does his best to comfort her and assure her that Bo and Lauren will find a cure but, with Halima dead, he's not too convinced of that, himself.
Bo reaches Sector 6, but is stymied by the man guarding the door. She tries to woo him with her humanoid wiles, but the guard doesn't bat for her team. Left with no recourse, she must use her succubus powers on him. She rejoices when she's able to feed and stop herself before she kills him. Lauren arrives, and the two enter Sector 6. They expect rows and rows of files, but discover a sterile room with a large, glowing tank in the middle, housing an Under Fae called a basilisk. Bo stabs the creature and snags a tissue sample, but the creature is too dangerous for them to leave in the hands of Behren, so they shut down the tank's life support and dash from the facility before they're found out.
Lauren creates an antitoxin from the tissue sample and administers it to Kenzi, who has been resting up at Trick's place. As soon as Kenzi makes a recovery, Lauren says her goodbyes. Lauren and Bo are too familiar for Dyson's comfort, but in order to protect Bo and the Light Fae, he can't let his feelings show.
Kenzi proves, with the ultimate gesture, that she€™s the best friend a succubus could ever ask for.
Dyson accompanies Bo to investigate the source of all evil only to have the script flipped on him.