The first new trailer for the long-in-development Mr. Peabody & Sherman movie is out, and, for some reason, there’s now a girl hanging out with its two bespectacled male protagonists. When Mr. Peabody’s rival, Mr. Peterson, brings his family over, Peabody charges Sherman with entertaining Peterson’s mean daughter, Penny. Sherman takes her in the WABAC machine, and—because they're just a couple of kids who don't know any better—the two disrupt the space-time continuum. And because it’s a movie and it needs a plot, Peabody, Sherman, and Penny must then use the WABAC machine to dress up in costumes and reset history, lest life as we know it become irrevocably disrupted.

Ty Burrell voices Mr. Peabody, the smartest dog in the world, while Max Charles voices Sherman, and Burrell's Modern Family co-star Ariel Winter plays Penny. Other actors contributing voices include Stephen Colbert, Leslie Mann, Allison Janney, Mel Brooks, Stanley Tucci, and Lake Bell. Danny Elfman provides the film’s score. Mr. Peabody & Sherman hits theaters March 7, 2014.