A high school freshman finds herself squaring off against monsters and joining a 1,000-year-old secret society in a new trailer for Rachel Talalay’s “A Babysitter’s Guide to Monster Hunting.” “Monsters took the kid I was babysitting,” Kelly (Tamara Smart, “The Worst Witch”) tells a disbelieving 911 operator on Halloween night.

If the teen has any hopes of finding Jacob (Ian Ho, “The Handmaid’s Tale”) and saving him from the monsters who took him, she’ll need to find help elsewhere. Cue Liz Lerue (Oona Laurence, “Lost Girls”), the chapter president of The Order of the Babysitters, a top-secret organization.

“Each of us has been through a monster attack. That’s why we’re here — to make sure what happened to us never happens to another kid,” one of the babysitters explains.

Talalay’s credits include “Riverdale,” “Supergirl,” and “Doctor Who.”

“A Babysitter’s Guide to Monster Hunting” hits Netflix October 15.