TV THIS WEEK: A Supernatural musical, Atlantis returns, and more

The CW's Supernatural celebrates 200 episodes this week, and it's doing it in style with a musical episode.

That's right, the monster-battling Winchester brothers will encounter one of the most frightening things they've ever seen in their travels this week: a group of fans who've turned their story into a musical adventure. Plus, Atlantis returns for season two, a two-hour Once Upon a Time, new Gravity Falls and more. 

Check out the week in TV below. What's on your watchlist?

Highlights of the Week

Sleepy Hollow (FOX) Monday, 9 p.m. - "Heartless" 

We're now well into Sleepy Hollow's second season, so let's take a minute and see how it's doing ratings-wise. Last year the series was a surprising breakout hit, drawing critical acclaim and very solid ratings for FOX. This year, plenty of critics and fans are still giving the show love, but its numbers are somewhat underwhelming. Last season the show premiered to 15 million total viewers (10 million watched the premiere in Live+Same Day), but this season's premiere only managed 9 million total viewers and 5.51 million Live+Same Day viewers. Now, obviously a series premiere will quite often draw many more viewers than the rest of the episodes, because people are having a little peek in at the show before deciding they don't want to watch it, so let's consider the rest of season one. At no point in the 13-episode first season did the show drop below 10 million total viewers, or 6 million Live+Same Day viewers. This season so far, the show's never touched 10 million total viewers, and Live+Same Day numbers have never topped 6 million. Perhaps more importantly, though, the show's also seen a significant drop in its key 18-49 demographic rating. Last season that number never dropped below 2.2 in Live+Same Day or 3.5 in total viewers, while this season it's never climbed higher than 3.5 in total viewers, or 2.0 in Live+Same Day. Last week's episode finished in fourth place behind the offerings of NBC, ABC and CBS, and though DVR numbers are often the kind of thing that can save a show like that, those numbers are dropping as well. Now, does this mean Sleepy Hollow is doomed? Absolutely not. These numbers may be lower, but they're not terrible, and on another night they might even look positively strong. There's still life in this show, but we have to wonder if the slide will continue, and how low it will go. This week, Ichabod and Abbie set out to battle a succubus. Check out a preview below.

Agents of S.H.I.E.L.D. (ABC) Tuesday, 9 p.m. - "The Writing on the Wall" 

Last season, Agents of S.H.I.E.L.D. suffered from a number of storytelling issues, and among the most signifcant was its wheel-spinning. Right from the beginning one of the show's central mysteries was How is Coulson alive?, and it was clear that even he didn't know. Viewers wanted to know what was up, and the show took its sweet time telling us, while often not offering something similarly compelling to fill the void. As a result, the show suffered. This season, things have improved, but there's another central mystery to solve: What's with that weird alien writing? Now, it definitely doesn't feel like we've been spinning wheels waiting for the answer to this question. It feels like we've been building toward something, like every episode has added another little ingredient to this story. This week, it seems that story's ready to unfold even more, in a big way, so this could be one of the cornerstones of season two. Now we just have to watch and see if the answers we get are satisfying. This week, the team investigates a series of bodies with the strange writing on them, and secrets are revealed. Check out a preview below.

Supernatural (CW) Tuesday, 9 p.m. - "Fan Fiction" 

200th episode special! - Supernatural is the little show that could, in its 10th season with solid ratings that just won't quit, and a positively rabid fanbase. So this week the show's celebrating 200 episodes with a musical tribute to the fans. That's right, it's a Supernatural musical, but in case you're worried that the Winchester brothers don't have the pipes to pull this off, never fear. They're not the ones doing the singing. See, the brothers are in the middle of an investigation when they just happen to stumble upon a group of teenage fans who are putting on a musical version of Supernatural, complete with teen girls dressed up in Sam and Dean stubble. It's a nice nod to all the fan fiction dedicated to the show, it's an opportunity for a little extra silliness, and it's bound to be cameo-packed. Check out a preview below.

Atlantis (BBC America) Saturday, 9 p.m. - "A New Dawn: Part One" 

Season premiere! - Well, there's no more Doctor Who until Christmas, but that doesn't mean BBC America's done with genre shows. This week the second season of Greek mythology-inspired fantasy drama Atlantis premieres. The show was always somewhat critically divisive in the U.K., and it got the same kind of mixed reviews here in America. Its ratings also steadily slipped in its first season, kicking off in the U.K. with more than 7 million viewers and finishing with less than five. Despite that somewhat rocky road, though, it performed well enough to return, and its creators have promised bigger stories and bigger action this time around. Now we just have to see if the show performs well enough to keep going for a third year. This week, Queen Ariadne seeks Jason's help to save her kingdom. Check out a preview below.

Once Upon a Time (ABC) Sunday, 8 p.m. - "Smash the Mirror" 

Two-hour event! - Once Upon a Time grabbed plenty of attention when it introduced characters from the Disney hit Frozen into its fairy-tale world this season, and the move translated to a boost in viewers from the slight slump that was season three. The Frozen-inspired story is still going on the show, alongside other arcs, and this week things seem to be coming to a head with a special two-hour episode. Once Upon a Time has found new success by building on an existing pop-culture phenomenon to create something new. Now we have to see if they choose to close this chapter of this four-season storybook, how they close it if they do, and what the show will do next. This week, Emma's powers are growing uncontrollable, and the Snow Queen will stop at nothing to start a battle between Anna and Elsa. Check out a preview below.

Monday, November 10

Gotham (FOX) 8 p.m. - "The Mask"

Gordon and Bullock check out a brutal fight club that features bouts between candidates applying for work at a financial firm. Meanwhile, upon his return to school, Bruce makes a new friend.

The Originals (CW) 8 p.m. - "Wheel Inside the Wheel"

Klaus demands that Esther release Elijah, but she reveals a few dark secrets from Klaus' past in an effort to make him an offer he can't refuse. Meanwhile, Hayley reconnects with Jackson; Cami becomes suspicious of her faculty adviser; and a visitor from Klaus' past arrives.

Gravity Falls (Disney XD) 8:30 p.m. -"Blendin's Game"

Blendin Blandin returns to fight Dipper and Mabel in a futuristic battle that could trap the two of them forever in time jail.

Star Wars Rebels (Disney XD) 9 p.m. - "Out of Darkness"

Hera and Sabine take the Phantom to an abandoned asteroid base to get supplies, but they become stranded there and are attacked by ravenous creatures.

Sleepy Hollow (FOX) 9 p.m. - "Heartless" 

Read more in our Highlights section above.

Scorpion (CBS) 9 p.m. - "Risky Business"

A musician, who created a controversial algorithm that generates hit songs, helps Team Scorpion find a music blogger's murderer. Meanwhile, Drew asks Walter to help him connect with his son.

Tuesday, November 11

The Flash (CW) 8 p.m. - "Plastique"

A bomb explodes downtown and the army, led by General Eiling, comes in and takes over the investigation, much to Joe's dismay. Meanwhile, Wells informs the team that Eiling experimented on his men to turn them into super soldiers; and Joe tries to get Iris to stop writing about "the streak."

Agents of S.H.I.E.L.D. (ABC) 9 p.m. - "The Writing on the Wall" 

Read more in our Highlights section above.

Supernatural (CW) 9 p.m. - "Fan Fiction" 

Read more in our Highlights section above.

Forever (ABC) 10 p.m. - "The Ecstasy of Agony"

A successful businessman's unusual death is investigated by Henry and Jo. Meanwhile, Abe's ex-wife resurfaces with a tempting offer.

Person of Interest (ABC) 10 p.m. - "Honor Among Thieves"

Shaw risks being detected by Samaritan when she joins a team of international thieves to monitor the latest POI. Meanwhile, Finch and Root go on a dangerous sabotage mission.

Wednesday, November 12

Arrow (CW) 8 p.m. - "Guilty"

Ted Grant is accused of murder when a body is found strung up in the Wildcat gym. In flashbacks, Maseo asks Tatsu to help jog Oliver's memory so he can remember where an informant for China White stashed key information; and Roy shares a secret with Felicity.

The 100 (CW) 9 p.m. - "Many Happy Returns"

Clarke is betrayed by someone she trusted. Meanwhile, Bellamy, Finn and Murphy (Richard Harmon) race to save a stranger; and tensions rise between Raven and Wick (Steve Talley).

American Horror Story: Freak Show (FX) 10 p.m. - "Bullseye"

A dangerous new act is unveiled by Elsa. Meanwhile, Stanley pressures Maggie to murder Jimmy; and Paul indulges in a secret romance.

The Almighty Johnsons (Syfy) 11 p.m. - "Charlie Truman"

The brothers celebrate Mike's new bar with a party, which ends on a sad note for Axl when his crush Gaia gets romantic with a complete stranger. Meanwhile, Ty's relationship with Eva has everyone concerned.

Thursday, November 13

Teen Titans Go! (TOON) 6 p.m. - "Body Adventure" and "Boys vs. Girls"

Cyborg falls ill and Robin shrinks to cell-size to help; boys and girls compete to find out which is the better sex.

Steven Universe (TOON) 6:45 p.m. - "Garnet's Universe"

Steven imagines Garnet's day.

The Vampire Diaries (CW) 8 p.m. - "Do You Remember The First Time?"

Elena's past comes back to haunt her; Jo opens up to Alaric about her tragic past; Stefan, Matt and Enzo resort to extreme measures when Tripp withholds information about his vampire-killing operation; Sheriff Forbes gets caught in the middle of a dangerous plan; Tyler and Liv grow closer; and Damon stumbles upon a startling clue that renews his hope.

Elementary (CBS) 10 p.m. -"Just a Regular Irregular"

A math genius, who is part of Sherlock's network of "irregulars" experts, stumbles upon a body while participating in a math puzzle competition. Meanwhile, Holmes reaches out to Kitty, after she learns about Kitty's past.

The Almighty Johnsons (Syfy) 11 p.m. - "Death's Cleansing Embrace"

Ty must decide whether to call the police on Agnetha, or help her cover up Eva's murder.

Friday, November 14

Legend of Korra ( - "Reunion" 

Korra returns to Air Temple Island. 

Haven (Syfy) 7 p.m. - "Mortality"

The gang are unsure how to handle an inquisitive CDC scientist, who could hold the key to curing their troubles -- that is, if she doesn't expose their secrets to the rest of the world first.

Grimm (NBC) 9 p.m. - "Dyin' on a Prayer"

Nick and Hank investigate a case involving clay-induced asphyxiation; Wu's suspicions about Trubel intensify; Elizabeth makes a major breakthrough in the pursuit of restoring Nick's powers; Monroe and Rosalee's inter-Wesen marriage sparks a cultural backlash; and Adalind hopes her mysterious visitor will help her escape the dungeon.

Constantine (NBC) 10 p.m. - "A Feast of Friends"

John must take into consideration what exactly he's willing to sacrifice in his battle with the underworld after an old friend accidentally unleashes a powerful demon with a killer appetite in Atlanta.

Z Nation (Syfy) 10 p.m. - "Going Nuclear"

The survivors square off against radioactive zombies when they arrive in a South Dakota town that's on the brink of nuclear disaster.

Saturday, November 15

Atlantis (BBC America) 9 p.m. - "A New Dawn: Part One" 

Read more in our Highlights section above.

Sunday, November 16

Once Upon a Time (ABC) 8 p.m. - "Smash the Mirror" 

Read more in our Highlights section above.

The Walking Dead (AMC) 9 p.m. - "Consumed"

Members of the group venture into a familiar location on a heroic rescue mission.

(Episode synopses via TV Guide)

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