Death at Their Heels — Margaret Goff Clark

When Rick receives an unexplained phone call in the night and wants to leave immediately on a wilderness camping trip, Denny is pleased at this sudden invitation from his brand-new, older stepbrother.

Only gradually does Danny find out that, this is no ordinary camping trip. Rick is running for his life.

In the depths of Canada's Algonquin Park, Denny responds with a new respect and awe to the nature around him, is drawn closer to his brother, and meets a rather unusual girl named Holly who takes him on a “wolf howl” led by the Park naturalists.

But the feeling of desperation dominates the trip as the boys try to keep ahead of the death that pursues them.