The Middle: Get a peek at the final Halloween episode

The Hecks have had some kooky Halloween costumes, and this year they’re going out with a “Deep Purple” bang. And EW has your exclusive first look.

Axl and Lexie, who are now in a relationship, decide to go as a couple… err, kind of. They dress up as brother-sister duo Donny and Marie Osmond in their classic “Deep Purple” ensembles.

Meanwhile, Sue is doing something a little more literal. “Sue finds it difficult adjusting to being a third wheel in their relationship, leading to a lot of awkwardness,” says showrunner Eileen Heisler. So Sue just leans and goes full third wheel for Halloween — literally.

During this year’s Halloween episode, Heisler says, “Frankie discovers a dark, disturbing secret about the Heck house, so she and Brick play amateur sleuths to get to the bottom of the mystery. Needless to say, they go a tad overboard trying to crack the case — they’re a little like the Scooby Doo gang of Orson… Spooky stuff!”

Even though this is the final season, showrunner DeAnn Heline says they didn’t think about this episode as “The Last Halloween Episode of The Middle.” Instead, she says, they used the episode as a way to tell arcs they were already building for the Hecks. “We actually have a huge whiteboard in our office with hundreds of unused ideas — things we’d like to do for future episodes — so we found a few that worked together nicely for Halloween. We knew if we didn’t do them now, we’d never do them.”

“By the way, any leftover ideas we don’t use by the end of the season will be sold to the highest bidder,” Heline jokes, “or will be on view when the whiteboard is displayed at the Smithsonian.”

The Middle airs Tuesdays at 8 p.m. ET on ABC.