Tom Mison stars in “Sleepy Hollow”

A show about an unlikely partnership is teaming up with its own unlikely partner. "Sleepy Hollow," now in its third season, is a fanciful, modern reimagining of the spooky old Headless Horseman tale. Chock-full of witches, time travel, demons and deadly secrets, "Sleepy Hollow" is best described as a fantasy/action/drama. How, then, will it pair with Fox's tried-and-true comedy/crime procedural "Bones" when the two cross over this week?

That question alone is likely to pull in many fans who are otherwise disinterested in one show or the other -- that's the genius of it. Network programmers hope that setting "Bones" fans up with two hours of "Sleepy Hollow" will result in those fans liking what they see and returning for more next week -- and vice-versa. These two fictional worlds collide in back-to-back crossover episodes when "Bones" and "Sleepy Hollow" air Thursday, Oct. 29, on Fox.

Michael Peterson, an executive producer of “Bones,” cleverly compared the upcoming crossover to one of Fox’s most beloved series -- a series set to make a big comeback next year:

“The ‘Bones’/’Sleepy Hollow’ crossover is like a great episode of ‘The X-Files,’ where the ‘Bones’ hour is the Scully, logic-based perspective and the ‘Sleepy Hollow’ hour is more Fox Mulder-esque. Put them together, and it’s going to be a great two-hour event that fans of both programs are going to love.”

In the first hour, the “Bones” team uncovers some disturbing remains and, during its investigation, runs into its “Sleepy Hollow” counterparts, who are investigating the same evidence. In the second hour, supernatural events in “Sleepy Hollow” lead the characters to seek help from the forensic team they encountered during their previous adventures.

"Bones" is now in its 11th season, and rumors that this will be its final run have started swirling. David Boreanaz (“Angel”), who plays Special Agent Seeley Booth -- who, along with Dr. Temperance “Bones” Brennan (Emily Deschanel, “Cold Mountain,” 2003), makes up the heart of the show -- told E! that he believes the procedural is nearing its natural conclusion:

“I think it’s time. I think that 11 seasons is great. I mean, one season is great! I don’t really count it as seasons but what we’ve given to the show and what we can do. For me, it’s great to see the show come to an end and do it the way we want to do it.”

Eleven years is impressive for any program, and it would be great to see the characters move on to something new, especially now that Brennan and Booth have tied the knot. Plus, ratings began to decline somewhat during season 10 -- it may be smart to call it quits before someone calls it for them.

Last year’s ratings slump is something “Bones” and “Sleepy Hollow” have in common, and Fox execs hope that a little shakeup and this intriguing crossover will help give both shows more stamina.

Emily Deschanel as seen in “Bones”

After a strong first season, "Sleepy Hollow's" viewership dipped last year, and many fans feared it would not be renewed for a third season. But season 3 is now underway, and the new showrunner at its helm is dedicated to returning the show to the success of its freshman year. Clifton Campbell -- former showrunner of both "White Collar" and "The Glades," two of USA Network's most successful original programs -- is in the driver's seat now, and he's made some changes that he believes will bring back some of the magic.

"I saw there were a few things that very subtly needed to be recalibrated to bring the fun back to the show, to bring the characters of Abbie and Crane front and center, and subtly build that [base] around them, so that the story could be a little more episodic," Campbell told TV news website Give Me My Remote.

On top of tweaking the show's dynamics, he's added some intriguing recurring characters to the mix, and at least two of them will be around all season. Joining police lieutenant-turned-FBI-agent Abbie Mills (Nicole Beharie, "42," 2013) and man-out-of-time Ichabod Crane (Tom Mison, "One Day," 2011) -- the Two Witnesses destined to fight the coming apocalypse -- are Betsy Ross (Nikki Reed, “Twilight,” 2008) and Pandora (Shannyn Sossamon, “A Knight’s Tale,” 2001).

Ross (who in real life is credited with creating the first American flag) is a figure from Crane’s past, with whom he shares a more complex relationship than he’s prepared to admit. Thanks to some mysterious supernatural ability, Ross is able to help Mills and Crane throughout the season.

Pandora, on the other hand, is not here to help. She’s in town using her own brand of dark magic to further some sinister plan that, as yet, remains shrouded in mystery. She’s the embodiment of the ancient mythological figure whose box housed all the world’s evil, so viewers can expect her to wreak havoc in Sleepy Hollow this season.

Exciting twists await fans of both "Bones" and "Sleepy Hollow" this year, and you don't want to miss any of the action. Catch the big crossover event with back-to-back episodes airing Thursday, Oct. 29, on Fox.