Guardian — John Saul

"All the right scares in all the right places." The Seattle Times
A telephone rings in the dead of night with shocking news for single mother MaryAnne Carpenter: her friends the Wilkensons are suddenly, inexplicably dead, their only child, Joey, a sad and silent adolescent and MaryAnne's godchild, abruptly orphaned. But as MaryAnne rushes with her family to the Wilkenson's ranch to embrace her young charge, disturbing questions mount. Was it an accident that killed her friends? Or murder?
Now, as winter transforms the ranch into a place of blinding, dangerous storms, a series of horrific murders, killings that suggest a raging animal and defy solution by the local police, draw ever closer to MaryAnne and her young family.