“The Witches” is also a significant departure for Ms. Schiff, a Pulitzer Prize winner. Unlike her previous books, which were anchored by a single compelling figure like Benjamin Franklin or Cleopatra, “The Witches” features a cast of about 100 characters, from Cotton Mather, the minister long vilified for orchestrating the wave of persecution, to household servants and farmers who were swept up in the chaos.

Instead of trying to explain the outbreak by attributing it to mundane outside forces, she felt she had to take the Puritans’ belief in witchcraft, and their deep fears and constant anxiety, seriously, she said.

“You have to make a crazy thing seem totally rational, and then at the end, you have to explain why it was crazy,” she said, “and that meant taking this deep dive into the 17th-century mind.”

Ms. Schiff first became fascinated by the Salem trials as a teenager in western Massachusetts. “Everybody goes through a Salem phase,” she said.

For decades, witches were far from her mind. After graduating from Williams College, she worked in publishing for about nine years. While a senior editor at Simon & Schuster, she had the idea for a biography of Antoine de Saint-Exupéry, the pilot and author of “The Little Prince.” At first she planned to assign it to a writer, but found she was so attached to the subject that she didn’t want to give it up. The resulting book was a Pulitzer finalist in 1995. Her next book, “Véra: (Mrs. Vladimir Nabokov),” a biography and a portrait of the Nabokovs’ marriage, won the Pulitzer in 2000.

Unlike many popular historians, Ms. Schiff deliberately parachutes into areas she knows little about for each book. “Having done Ben Franklin, I didn’t want to go do John Adams,” she said. Instead, she wrote a biography of the ancient Egyptian ruler Cleopatra, which sold about 800,000 copies.

Salem was an even more daunting undertaking, because it required her to paint a portrait of an entire society, one that seemed more foreign and esoteric in some ways than Ptolemaic Egypt.