Batman and Harley Quinn are forced to join forces against Poison Ivy in “Batman and Harley Quinn.” (Warner Bros. Animation)

Harley Quinn’s animated homecoming is quite the grown-up affair in Warner Bros. Animation’s latest straight-to-home-video DC Comics movie.

Harley Quinn is now a movie star (“Suicide Squad“), soon to be starring in her own movie (“Gotham City Sirens”) and one of the most popular characters in the pages of DC Comics, where she appears in multiple series, including her own.

But it was “Batman: The Animated Series” where she appeared for the first time, and it is that animated universe where “Batman and Harley Quinn” (available now on 4K, Blu-ray and digitally) takes place. Her equal billing in the movie’s title shows how far Harley has come since her cartoon beginnings, and she gives the story some dark and sexy moments, since she’s not confined to after-school rules of animated television.

The movie serves as a reunion of sorts, as Batman and Nightwing (who was a teenage Robin the Boy Wonder when BTAS began in the early ’90s and is now an adult) are forced to work together with Harley to stop Poison Ivy and the Floronic Man from turning every living thing on Earth into a plant.

(Warner Bros. Animation)

There are certain elements that just have to be there for a BTAS story to work, and they’re all there. Bruce Timm, one of BTAS’s key creators during the show’s original run on television and Harley Quinn’s co-creator, is a producer on this movie. The classic BTAS animated style, cartoony but dark, featuring a square-jawed Batman with backward-pointing ears on his cowl, is there.

Perhaps most important are the voice actors. There is no way you can have a BTAS story without the talents of Kevin Conroy (Batman) and Loren Lester (Nightwing). This dynamic vocal duo is the heart of BTAS. Arleen Sorkin (the original animated voice of Harley Quinn) isn’t around this time, but Melissa Rauch provides her best high-pitched, take-no-nonsense Brooklyn accent as Harley. This is the first notable WB/DC animated release since the retirement of legendary voice director Andrea Romano, but casting and voice director Wes Gleason steps in and makes sure this new take on a beloved universe sounds the way its supposed to.

That new take involves making this universe a bit more naughty. BTAS was always a show both kids and adults could enjoy during its television run, but it existed in a strictly PG world. “Batman and Harley Quinn” is rated PG-13 and the producers take that rating as far as they can go with it. Not to say we haven’t seen DC’s animated movies enter R-rated territory, which “Justice League Dark” and “The Killing Joke” did recently. But there’s something about this particular animated world operating at a more adult pace, in terms of actions and dialogue, that feels a little shocking at times to watch.

Melissa Rauch voices Harley Quinn in “Batman and Harley Quinn.” (Warner Bros. Animation)

There’s sex (you don’t see it, but you know it happens), dark and dirty humor, plenty of all the bad words a PG-13 rating allows, most of them coming from Harley Quinn. And Harley and Ivy’s more-than-friends relationship is hinted at a lot more strongly than it ever was on BTAS.

Timm and his collaborators realized that any new BTAS movie would just feel like another episode of the original show if chances weren’t taken. A wild card character like Harley Quinn provided the opportunity to kick up the maturity a notch.

“Batman and Harley Quinn” feels like a thank you and a sly wink to the audience that made BTAS a part of their childhoods and who are now adults. There’s enough here for old and new fans of this universe, and hopefully this isn’t the last time WB/DC lets this Batman world stay up a little later.

Read more:

‘Teen Titans: The Judas Contract’ turns a classic DC Comics tale into an animated hit

Margot Robbie on becoming Harley Quinn and ‘the most unpleasant thing I’ve ever done’

Harley Quinn of ‘Suicide Squad’ could be 2016’s most popular movie character. How did she get started?