One of the 664 two-inch uranium cubes produced in Nazi Germany during a failed attempt to create a nuclear reactor in World War II. (John T. Consoli/University of Maryland)

A cube of uranium. A Nazi plan to build a nuclear bomb. A search for the fate of the remaining pieces of an experiment that might have altered history.

It sounds like a basis for a war thriller. Instead, the story appears in the latest issue of Physics Today, the membership magazine of the American Institute of Physics.

It’s the tale of 664 uranium cubes produced by researchers in Nazi Germany. They sought to crack the nuclear code in a subterranean laboratory in the “atom cellar” of a castle in Haigerloch. But the experiment failed.

When a two-inch cube from the failed reactor made its way to Timothy Koeth, a physicist at the University of Maryland at College Park, his curiosity was piqued.

Miriam Hiebert, a doctoral student in the materials sciences and engineering program there, volunteered to help him learn more about its past.

Despite the genius of physicists such as Werner Heisenberg, the German nuclear weapon program was stymied by bureaucracy during World War II.

Instead of pooling its resources, Nazi Germany split the researchers into three competing teams, and the very contest the Germans thought would fuel innovation ended up stifling it.

But they came much closer to a nuclear weapon than scholars previously thought.

Koeth and Hiebert used archival materials to reconsider the Nazi nuclear program. What they uncovered is unnerving.

“If the Germans had pooled rather than divided their resources,” Koeth and Hiebert write, “they would have been significantly closer to creating a working reactor before the end of the war.”

The researchers want to track down all of the cubes. The account of the Nazis’ failed nuclear program is an intriguing read — one that turns what could be seen as a historical curio into a much more ominous story.