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The Thirteenth Degree a Hypatian Conspiracy
Paperback
Mystery & ThrillerHistorical Fiction
ISBN13: 9781946505576
Publisher: Sara Madden
Published: Aug 27 2026
Pages: 398
Weight: 0.91
Height: 0.99 Width: 5.50 Depth: 8.50
Language: English
For sixteen centuries, someone has been correcting history.
Seraphina Marchand notices errors for a living. A multilingual paralegal specializing in international cultural property law, she has built a career around discrepancies other people overlook.
Then, inside a basilica near Quebec City, she finds one she cannot explain. A mural identifies an early Christian apostle as a man. The Greek says she was a woman. Behind her head, an eight-pointed star has been deliberately rotated thirteen degrees.
It should be meaningless.
It isn't.
When manuscript fragments discovered in Paris reveal the same thirteen-degree anomaly-and an archivist connected to them dies under mysterious circumstances-Seraphina is pulled into a trail of encoded knowledge stretching from modern Quebec to Paris, Athens, Delphi, Constantinople, and fourth-century Alexandria.
At its beginning stands Hypatia: mathematician, astronomer, philosopher, and a woman whose work survived only in fragments after her brutal murder in 415 CE.
But Hypatia was not the only woman history altered.
Junia, named an apostle in the earliest Christian tradition, became a man in later manuscripts. Kassia, one of Byzantium's great female composers, left music capable of carrying information long after ordinary records could disappear. Across centuries, women whose authority proved inconvenient were renamed, reclassified, diminished, or erased.
Someone noticed.
And they left a correction.
Hidden inside planetary tables, hymns, manuscript margins, sacred architecture, and a recurring thirteen-degree rotation is evidence of a lineage Seraphina's own family has spent decades trying to understand: the Rose Line.
Now someone else is following it too.
As Seraphina discovers that her mother's secret research and her late father's work are entangled with the same pattern, the investigation becomes dangerously personal. A shadow network known as the Custodians of Stability has survived not by destroying history outright, but by controlling what institutions preserve, catalog, teach, and remember.
And Seraphina is getting close enough to threaten the record they created.
To uncover the truth, she must decipher a mathematical system designed to survive its makers, confront what was hidden inside her own family history, and answer a question more dangerous than any conspiracy:
How much of history disappears not because the evidence is lost-but because someone decides whose knowledge is allowed to count?
Blending historical mystery, mathematical codes, religious history, astronomy, and a fast-moving international conspiracy, The Thirteenth Degree is an intellectual thriller about the women history tried to erase-and the people who refused to let them vanish.
The error was thirteen degrees.
It was never an error.
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