When a Darkness Falls — Paul Zindel

Someone is killing women in the high-priced canyons around Los Angeles. Someone who strikes ruthlessly, randomly, leaving his red badge of rage on his victims’ bodies…For Jack and Marjorie Krenner and their two small children, life in their new home among the rich and famous is a dream come true. Until slowly they wake to the fear that walks the night. And soon they know that nothing, not the iron gates nor the alarms nor the watchdogs, can protect them from a killer who is closer to home than they dare imagine.