Of all the tragedies inflicted upon American slaves in the years before that country’s civil war, one of the worst was the breaking up of families. Husbands and wives, put up for sale at slave auctions, were often bought by different buyers and never reunited. Children lost their parents and their siblings as slaveholders calculated the value of human property according to long-term potential or diminishing shelf life.

Brian Prince’s A Shadow on the Household gives us a heart-rending glimpse of this appalling era in history by chronicling the Weems family of Rockville, Maryland. Owned and kept as a unit by landholder Adam Robb, their lives were torn apart after Robb died in 1847, leaving their fate in the hands of the Harding family. The Hardings split up the Weems family and sold them to buyers in far-flung regions, leaving the heartbroken John and Arabella Weems with the prospect of never again seeing some of their seven children.

This epic story by Prince — a descendent of slaves who fled to Canada before the Civil War — reads like a tightly written novel. Its sympathetic characters are deeply affecting as they race against time to ensure the freedom of loved ones before they are relocated to the Deep South and an inescapable, cruel fate.

Important Canadian aspects of the story are given due emphasis, such as the workings of the Underground Railroad that helped slaves flee to Canada. Americans who created and supported this escape route did so under threat of severe punishment, due to the passage of the Fugitive Slave Act. The law, enacted in 1850 by the U.S. Congress and enforced in the “free” states, decreed that all runaway slaves had to be brought back to their masters — a legislative “compromise” designed to appease the slave states.

The law forced individuals and organizations to act secretely when helping slaves reach freedom, which for an estimated 40,000 of them, proved to be Canada.

A great deal of moral and financial support for this movement came from Britain, albeit with some fierce debates over the spending of donated funds. Many anti-slavery advocates believed certain slaves’ freedom could be bought at auction, while others argued such tactics prolonged slavery and drove up prices for others trying to escape bondage.

Some of Prince’s most moving passages describe the dehumanizing aspects of slave auctions. At one, “As the sale in human flesh began, [anti-slavery crusader Dr. Ellwood] Harvey was saddened to see the old men relinquish whatever little bit of pride they possessed and exaggerate their infirmities and worthlessness so they would not be sent to the southern cotton fields. Those who were most successful at this ruse soon learned that they were worth only between thirteen and twenty-five dollars.”

Ultimately, however, the tale is one of bravery and triumph, as in the successful escape by 14-year-old Maria Weems, who eludes her pursuers by dressing like a boy and changing her name. The bonds of family prove too strong to be broken by a cruel system in an age that’s hard to imagine in the 21st century.