Should we judge "Sleepy Hollow" by the monster of the week or the mythology of the week? It's still an open question in these early stages, as the show finds its way and figures out how to strike the right balance.

Let's go with the monster first, since that's what worked the best in episode three. One could even call "For the Triumph of Evil" a modest triumph by monster standards. (Look at that, I just did.) The Sandman who haunts Abbie's dreams and drives demon deniers to their deaths was legitimately creepy. There was something very "Pan's Labyrinth"-era Guillermo del Toro about the tall, pale being with gaping holes for eyes, and I kept wondering if it was Doug Jones somewhere inside there. (It wasn't.) Beyond the Sandman's look, the episode's director, John F. Showalter, did his best James Wan imitation in maximizing the effectiveness of the Sandman's every unsettling appearance. All in all, it was admirably scary stuff for network TV.

But the Sandman was just the window dressing for a plot designed to shed light on Abbie's past, and what really happened when she and her sister Jenny saw the demon in the woods when they were kids. As it turns out, they went missing for four days (what happened during that period we still don't know, and it doesn't seem that Abbie knows either). When they were found, Abbie insisted on keeping everything quiet so that the girls wouldn't be removed from their current, happy, foster home. But Jenny had other ideas and told the police exactly what they saw. Without Abbie backing her up, Jenny was institutionalized and the sisters have been estranged ever since.

It's a juicy backstory with enough holes (the missing days, Abbie's negative feelings about her biological parents) to revisit in episodes down the line. It simply wasn't very well done. This should've been a showcase for Nicole Beharie, but her performance was a little too one-note -- angry, hostile -- throughout, mostly because the episode didn't give her very much to play. The guest stars were even worse. (John Cho and Clancy Brown were definitely missed.)

But shaky acting in genre television is nothing new, and the beating heart of "Sleepy Hollow" -- the chemistry between Beharie and Tom Mison -- remains very much intact. Mison, per usual, was in top form even as Ichabod was mostly a reactive presence this week. He nailed the weekly dose of fish out of water comedy (Ichabod discovers energy drinks ... and the shameful treatment of Native Americans since the American Revolution) with typical conviction that sells even the show's wackiest moments.

This was a relatively simple episode compared to the first two. It opens with Abbie's "prophetic dream," in which Ichabod tells her to stop lying and the truth will set her free. It climaxes with Abbie facing off against the Sandman. She stops lying. The truth sets her free.

In the final twist, Abbie discovers Jenny has escaped her cell at the institution. So let's hope there's more to mine from their sibling strife yet.

Odds and ends:

- "Unless you have an encyclopedia of faceless nightmare monsters..." Or Rupert Giles. He'd at least know where to find one.

- There was enough of a "Nightmare on Elm Street" vibe to this episode that it started to feel like homage, especially to the cult favorite threequel "Dream Warriors." From Jenny at the institution, to Dr. Vega leaping off the side of the building, to the idea that Abbie and Ichabod can enter the dream realm at will to take on the monster directly. And, of course, if they die in the dream they die in real life.

- "Last thing we need around here is another episode of 'The Twilight Zone.'" Um, I do hope the show has something more in store for Orlando Jones' scolding captain than just spouting one-liners like that.

- Ichabod quotes Edmund Burke's "The only thing necessary for the triumph of evil is for good men to do nothing," and just like that, we have our title.

- The Chordettes' "Mr. Sandman." Nice.