Few shows are as perfectly suited to do Halloween episodes as 'Grimm,' so we're hoping they deliver with tonight's episode "La Llorona." Last week's episode "The Other Side" raised the stakes for the Captain Renard/Juliette kiss, so we're hoping that comes into play, but as it's Halloween time, we're guess this is more of a one-off.

The episode opens with the quote "On many a dark night people would see her walking along the riverbank and crying for her children." By a bridge a Mexican father and son go fishing and see a woman crying and walking into the river. The father goes over to save her, but while in the water he sees his son go walking off with the woman and the child is nowhere to be found.

Nick is in his camper looking for a weapon and we see that's it's Halloween in Portland and that no one takes it more seriously than Monroe - who says in his culture Halloween is bigger than Christmas. Nick was bringing the weapon for Monroe. It's a flail, and Monroe has it attached to a skeleton which he uses to crush a pumpkin. Nick gets called in, while in the water we see the spirit woman ("La Llorona") in the dream of a woman who's been tracking the disappearances. Nick's called in on the missing kid, and there's a language problem as the father doesn't speak English. A kayaker caught video of the woman, and they take it back to the station. Nick calls in Juliette to translate. Back at the station - after an awkward moment between Juliette and Renard - Juliette serves as interpreter, but they get no leads. The female investigator paces, seeing the missing child alert, and it turns out she's a Wesen. She books a flight to Portland.

They go to man's house looking for the missing kid Rafael, and one of the neighbors pulls Juliette aside to say she knows who took the kid. The neighbor says it's La Llorona, and she identifies the picture of La Llorona. The woman also recognizes Juliette's scratches as a curse. Nick asks Juliette to stay, and she's a little concerned about what the neighbor said but sticks around. Renard's having a conversation about his secret life when the investigator women, Valentina Espinoza, shows up at his office. Nick and Hank aren't getting anywhere in their investigation, when Valentina joins them. She says that La Llorona will take two more, and if she isn't caught the children will be dead by morning.

At Monroe's the kids are taking treats, when Monroe stops kids from bullying a girl. Back at the station, Valentina reveals La Llorona's M.O., and that she's been on this for five years. When Nick shows her the picture of La Llorona he sees a flash of Valentina's Wesen side, and she says that there's a pattern to where La Llorona takes the children. Renard asks to get the Albuquerque records of Espinoza's work, and then checks on the whereabouts of Adalind, who went to Vienna (as we know from last week). As children and adults play in the forest, we see a young girl run off, and guess what happens to her? She sees a woman crying by the beach.

Back at the station Valentina maps where La Llorona will be taking the children, and they now know where the last child will be taken from. Rafael's father then gets the news that another child was abducted The neighbor lady shows up, and tells Julliette that she's tired and her world is falling apart, and that she has to choose between two people. Nick, Hank and Valentina go to the crime scene of the missing girl when Renard shows up to bust Valetina, who obviously doesn't work for the government -- it turns out she was kicked off the force. She then reveals her Wesen side and she notes that Nick's a Grimm as they take her into custody. La Llorona brings the second child to her haunted house, and puts her with Rafael. The kids think La Llorona is an angel. Back at the station Renard grills Valentina, who reveals that five years ago her niece was taken. Renard says it's the FBI's case now. Nick and Hank say they believe Valentina, but can't do anything about it, so they head to the camper and find a picture of La Llorona, who's named as such by Nick's ancestors. Back at Monroe's, the kids he reprimanded plan payback.

In the camper, Nick reveals that Nick's ancestors couldn't figure out the woman's game plan either, and find that there's been issues of this since the sixteenth century. Nick and Hank decide to go after her, even without a game plan. At Monroe's, the kids break his window, which gets Hank to act a little Wesen-y. Nick and Hank go to Valentina at the station hoping she might understand some of what they've read, and then take her with them. While they take her to the car, the third kid is kidnapped. They figure out that she drowns the children in the middle of their map, and they have until midnight. La Llorona leads the kids to the river, while Nick and Hank and Valentina run to save the children. La Llorona is enacting her part of the ritual as three children's spirits rise out of the water. Nick and company run towards the woman and children, and Nick takes La Llorona under water where they tussle. Eventually, La Llorona falls to the bottom of the river and disappears. The good news is that the kids are safe, the bad news is they don't know if they stopped La Llorona. But the families are reunited, which makes Juliette happy. Renard chews them out a little, but knows they did the right thing as Juliette flashes to her conversation with the neighbor lady while looking at Nick and Renard. The bully kids are hanging outside looking at the video they took of breaking Monroe's window when Monroe steals their phone. The kids say they're not afraid of Monroe, which leads him to go werewolf. Which is the punchline we've been waiting for.

For a Halloween episode this was reasonably Network-television creepy, and though Monroe got sandwiched in (it feels like they're waiting for Rosalee to come back to give him more to do), it was a good episode for the season. Though there are some elements of the macabre to 'Grimm,' for the most part it's a fun mystery show, and it was nice to see them try to go a little darker with the material. Again, there's a limit to how far they could go, but perhaps because we think 'The Blair Witch Project' is a scary movie, the kids being put under a trance had some creep factor. But what did you think? Leave your thoughts on "La Llorona" in the comment section below.