The Dark Series brings together the three books in the Dark Series by bestselling serial killer author Susan Lund.
Book One: Long Dark Night
Book Two: Deep Dark Forest
Book Three: Cold Dark Water.
About Long Dark Night:

The Dark Series brings together the three books in the Dark Series of serial killer thrillers by bestselling serial killer thriller author Susan Lund.

Book One: Long Dark Night

Book Two: Deep Dark Forest

Book Three: Cold Dark Water

About Long Dark Night: Book One:

Introducing LONG DARK NIGHT, the first book in the Michael Carter Cold Case Thriller Series by Susan Lund.
Two teenage boys went missing from a park in King County a decade ago. While one of the boys was found days later, his body discarded in a ravine in the forest on Tiger Mountain, the other boy was never found.
Until now.
After a property developer's front end loader unearths the skeletal remains of several teenage boys from around Washington State, the missing boy's remains are identified. As a result, King County Cold Case Investigator Michael Carter looks into the cases. He suspects they are linked to several current disappearances of teenage boys who were either living on friend's sofas or on the streets. Believing he has another serial killer on his hands, Carter works with the FBI's CARD Team to try to locate the missing boy.
When Carter gets too close for comfort, he becomes the target of the serial killer's rage, leading to a showdown between the two adversaries on one long dark night...