In 1932, as the Nazis rose to power in Germany, a Jewish librarian in Frankfurt published a catalog of 15,000 books he had painstakingly collected for decades.

It listed the key texts of a groundbreaking field called the Science of Judaism, in which scholars analyzed the religion’s philosophy and culture as they would study those of ancient Greece or Rome. The school of thought became the foundation for modern Jewish studies around the world.

In the tumult of war, great chunks of the collection vanished. Now, librarians an ocean away have determined that most of the missing titles have been sitting for years on the crowded shelves of the Leo Baeck Institute, a Manhattan center dedicated to preserving German Jewish culture.

The story of how the hundreds of tattered, cloth-bound books with esoteric German titles ended up in New York includes impossible escapes, careful scholarship and some very heavy suitcases. And while the exact trails of many of the volumes remain murky, they wind through book-lined apartments on the Upper West Side, across a 97-year-old woman’s cluttered coffee table and into a library’s cavernous stacks.