Deep in the forest, two teens run for their lives with two vulture-like creatures called Geiers hot on their trail. When they hit a river, one of the teens, Steven, slips in and floats away. Before Kevin can help him, he's grabbed from behind by the Geiers who pull him screaming into the woods. Kevin is dragged past a fire pit into a barn, where the body of a young girl is being thrown into the flames. The next morning, we see Steven's lifeless body float down the river and over a large waterfall.
Over coffee, Nick confesses to Monroe that he wants to tell Juliette about being a Grimm. Monroe warns that nothing good can come of it and notes that Nick should breakup with her for her own safety. Nick refuses to give up on Juliette, determined to find another way. Monroe admits that Grimm creatures can be seen by humans only if they decide that they want to be seen, but most humans simply can't process the gravity of that event. Transforming for Juliette would likely have devastating consequences.
The body of the boy is discovered washed up on the river. He's strikingly pale, and two puncture wounds on his neck lead Nick and Hank to believe that the body was drained of blood. The only thing on him is a puka shell necklace. According to Harper, the boy died from drowning, but he probably drowned because he was incredibly weak from loss of blood. Nobody puts I.V. needles in their neck by accident; this is definitely a homicide.
Nick and Hank are called to a particularly unusual car crash. The contents of the SUV are strewn about: human blood, livers and hearts. As the driver's pried from the car and dies on the gurney, Nick sees him transform into a Geier. Later, Nick and Hank test the blood and organs and find that the blood from the vehicle matches that of Steven. However, the organs do not; they appear to belong to a number of different people. It looks like somebody has been harvesting human organs... and not from a hospital. Additionally, the organs are young and healthy, leading Nick and Hank to believe that street kids are the main target.
The phone number of the organ dealer leads the police right to the source, where countless human organs are found drying in a greenhouse-like contraption. The police take down the only man at the location and find that he's received a number of phone calls from a free medical clinic - the same clinic that the street kids frequent. After busting into the clinic, Nick threatens the only nurse left to give up the location where they're operating on the children.
Later, after studying up on Aunt Marie's books, Monroe confirms Nick's suspicions that Geiers are his primary suspect. These creatures harvest human parts for creature enhancement. Apparently, humans are the equivalent of exotic animals in the Grimm world. Nick persuades Monroe to go to one of these shops for human organs and bring proof. Monroe buys Nick "Gallenblase," which is ground up human gallbladder. Nick later goes back and confronts the storeowner, threatening him until he gives up his contact who's delivering the goods.
Gracie and Hansen are snatched off the street by the office manager from the clinic and thrown into a white van. Hansen discreetly leaves a trail of puka shells as they're led to the cabin in the woods and prepped for surgery. The same female doctor from the clinic performs organ-harvesting surgery on an innocent victim as Gracie, Hansen and the previously missing Kevin await their fate.
Nick and Hank gather Steven's identity and track down his PO box. In the post office, they find a kid with a similar necklace, which leads them to the sellers, two young teens. These "street kid" siblings Gracie and Hanson knew Steven well; he got work at a ranch a month back and they haven't seen him since. Their last encounter was at the local free medical clinic. Nick and Hank go to the clinic to follow up, but Steven's medical records don't provide any clues.