With her housemate Blake away and her lover Chase also absent, Sam Westin, at loose ends, embarks on a backpacking trip in the North Cascades, hoping to photograph the elusive gray wolves. Blake, reeling from a recent breakup, has taken a six-week job far away in Evansburg, caring for three gorillas while their owner, Dr. Grace McKenna, is on vacation. But events take a dark turn when the baby gorilla is shot by an intruder, prompting Grace's lover, Detective Finn, to investigate.

Sam's impromptu trip becomes dangerous when she finds a corpse and then stumbles upon an injured immigrant and pack horse carrying drugs. After a gunshot forces her to flee her campsite, Sam faces a perilous cross-country journey with the injured man and horse in tow.

In Evansburg, while following the trail of the gorilla shooting, Detective Finn stumbles upon a murdered woman in a nearby abandoned house and her child hiding in the gorilla barn. With both investigations going nowhere fast, it will take Sam visiting Blake and the gorillas to spot a clue that may be the link needed to solve all the crimes.