THE UNWILLING by John Hart; St. Martin’s (384 pages, $27.99)

Engrossing — and effective — historical mysteries don’t have to take place during eras hundreds of years ago. Often, the most gripping historicals take place during our immediate past as John Hart demonstrates in “The Unwilling,” set in 1972 during the height of The Vietnam War.

Hart’s seventh novel delivers an intense story about a family divided and falling apart, a metaphor for the country’s fractious climate. “The country was wounded and hurting. Was divided too big a word?”

In addition to being a story about family bonds, “The Unwilling” also is about boys who would be men with the pall of the draft hanging over their heads after high school graduation.

Jason French served as a

Marine in Vietnam, apparently killing many enemies. But Jason didn’t come back a hero — he returned a heroin addict and spent time in prison for violent crimes associated with his drug habit. His twin brother, Robert, who Jason knows was more loved by his parents, was killed in Vietnam.

Unhappiness awaits Jason in his Charlotte, N.C., hometown. He wants to reconnect with his youngest brother, Gibby. But his mother, still reeling from Robert’s death, refuses to allow Jason in the house and demands Gibby stay away from his brother. But Gibby is a teenager, “tired of being the youngest, the sheltered, the only one unproven by combat or adulthood,” so he sees Jason on the sly.

Jason becomes the suspect when a woman he dated is murdered. Gibby’s attempts to prove Jason innocent puts him against his father, a police detective.

Hart skillfully mines the details of the early 1970s and the impact the Vietnam War had on the country in “The Unwilling.” Although the plot occasionally dips into too much violence, the story’s strength is its deep examination of characters and the country. Each is a product of the times while trying to look to the future.