When Nathan was five, his father left him and his mother for a 19-year-old dental hygienist. Since then, his dad (or “Old Man,” as Nathan refers to him) hasn’t managed more than the occasional phone call and half-hearted (often late) birthday present. So Nate – as our protagonist prefers to be called now that he is 16 – is understandably perturbed when his absentee father shows up at the beginning of what had promised to be the “Best Summer Ever,” to whisk him away to Ho Chi Minh City. The story that follows, told in Nate’s voice, delves into the history of the Vietnam War (Old Man is a vet, and a conflicted one) as well as the father-son relationship.

Old Man isn’t a dark book, though it goes to dark places. But it is not for the faint-hearted. Examining complex moral and ethical issues, Poulsen lets his characters exist in (and at times grapple with) uncomfortable but realistic ambiguities.

Nate is a fully realized character rather than simply a cipher for his father’s admittedly more spectacular biography. His crippling fear of dogs, age-inappropriate stress headaches, and first fumbling relationship all contribute to this sense of authenticity. Nate is believable and appealing, complete with the contradictory swagger of his age, and you’re rooting for him even when he’s at his most blatantly adolescent.

Although at times it seems as though the reader is following Old Man just as blindly as Nate (long, silent car rides and hikes feel as monotonous as they would in real life), the emotional impact of the setting packs a wallop. Poulsen doesn’t go in for the tearjerker ending the narrative sets up as a possibility. Instead, this is a grown-up book about the horrors of war and a boy discovering the grey areas of life, told in an irresistible, realistic young voice.