To a dog, there is no such thing as "fresh air." Every breath of air is loaded with information. In fact, what every dog -- the tracking dog, of course, but also the dog lying next to you, snoring, on the couch -- knows about the world comes mostly through his nose. Alexandra Horowitz, a research scientist in the field of dog cognition, unpacks the mystery of a dog's worldview. With her family dogs, Finnegan and Upton, leading the way, Horowitz sets off on a quest to make sense of scents, combining a personal journey of smelling with a tour through the cutting edge and improbable science behind the olfactory powers of the dog. From revealing the spectacular biology of the dog snout, to speaking to other cognitive researchers and smell experts across the country, to visiting detection-dog training centers and even attempting to smell-train her own nose, Horowitz covers the topic of noses -- both canine and human.