When the influenza pandemic hit the U.S. between 1918 and 1920, Americans wanted answers. Their questions weren’t limited to what caused the pandemic or might prevent the next one. They struggled with more eternal concerns, such as what happens to us after we die and whether it’s possible to communicate with dead loved ones.

The flu pandemic wasn’t alone in spurring this search for meaning. World War I, which ended in November 1918, had racked up a worldwide death toll of 20 million soldiers and civilians, according to one estimate. And if that wasn’t sufficiently staggering, the influenza had taken at least 50 million lives. In both cases, most victims were young—between 20 and 40, in the case of the flu—and left behind parents, spouses, sweethearts and children.

Not surprisingly, spiritualism, which promised a window into the afterlife, saw a sudden resurgence in the United States, Great Britain, France and elsewhere. A February 1920 headline in the New York Sun said it all: “Riddle of the Life Hereafter Draws World’s Attention.”

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The two most prominent proponents of spiritualism were British: Sir Arthur Conan Doyle and Sir Oliver Lodge. Doyle was, of course, the creator of Sherlock Holmes. Lodge was a respected physicist known for his work with radio waves.

Both men had a longtime interest in the supernatural, and both had lost sons in the war. Lodge’s son Raymond had been struck down by a shell fragment while fighting in Belgium in 1915. Doyle’s son Kingsley had been wounded in France in 1916 and died of pneumonia in 1918, likely brought on by the influenza pandemic. Doyle also lost his younger brother to the flu in 1919, while his wife’s brother had been killed in Belgium in 1914.

After the war, both men lectured widely in the U.S. and also wrote books describing their psychic experiences.

Lodge’s 1916 book, Raymond, or Life and Death, describes numerous purported contacts with his late son. Lodge and his wife met with a variety of mediums, who practiced such techniques as automatic writing and table tilting to communicate with the dead.

In automatic writing, the spirit supposedly guided the medium’s hand to write out messages. In table tilting, participants typically sat around a séance table while the medium recited the alphabet. When the medium arrived at the letter the spirit had in mind, the table would tilt, turn, levitate or make some other inexplicable move. Still other mediums went into trances and allowed the dead to speak directly through them.

In his messages, Raymond offered a comforting version of the great beyond, complete with flowers, trees, dogs, cats and birds. He repeatedly assured his parents that he was happy. He told them he’d reconnected with his late grandfather plus a brother and sister who died in infancy, and made many new friends. He reported that soldiers who’d lost an arm in battle found it magically restored, although those who were “blown to pieces” took a bit longer to become whole.

In a 1920 visit to New York, Lodge told a reporter that he was still in touch with Raymond, as well as other fallen soldiers. “I have talked to a good many lads killed in the war,” he said. “They have not gone out of existence. They tell me it is pretty much over there as it is on this side.”

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Arthur Conan Doyle had a similarly soothing message. He claimed to have heard from his son during a 1919 séance, calling it “the supreme moment of my spiritual experience.”

As Doyle remembered, “A large, strong hand then rested upon my head, it was gently bent forward, and I felt and heard a kiss just above my brow. ‘Tell me, dear, are you happy?’ I cried. There was silence, and I feared he was gone. Then on a sighing note came the words, ‘Yes, I am so happy.’”

On a 1922 lecture tour Doyle told a reporter that, “I have many times spoken with my son,” and that he remained happy. “You see, a so-called dead man goes to a happier plane,” Doyle explained. “There is no crime, no sordidness, and it is many, many times happier.”

Nor, Doyle claimed, was he unique in communicating with his son. In 1918 he said he knew of 13 mothers who were in touch with their dead sons. By the following year, the number had reportedly risen to 24.

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While Lodge and Doyle appear to have been sincere in their beliefs, they inadvertently gave a boost to scam artists who saw money to be made from grieving families and the simply curious.

“Since the war,” the New York Sun wrote in 1920, “pretended mediums, long since exposed, have revived their ugly trade and are again in this and every large city fattening on the offerings of the distressed in heart.”

This proved too much for Harry Houdini, the famous escape artist, who had successfully eluded both World War I service and the influenza pandemic. Though a friend of Doyle, Houdini, with his deep knowledge of magic tricks, was a natural skeptic of spiritualism, which he had studied for years.

While Doyle toured the world promoting spiritualism, Houdini spent his time exposing fraudulent mediums and reconstructing how their trickery worked. In 1919 alone he claimed to have attended more than 100 séances, not one of which had made a believer of him.

“After 25 years of ardent research and endeavor,” he wrote in his 1924 book, A Magician Among the Spirits, “I declare that nothing has been revealed to convince me that intercommunication has been established between the Spirits of the departed and those still in the flesh.”

In 1926, Houdini was called to testify before a Congressional committee that was considering a bill to outlaw mediums, clairvoyants and fortune tellers in Washington, D.C. Members of the latter groups packed the audience, and the hearing soon became a shouting match between them and Houdini—and had to be adjourned for a time.

“There are millions of dollars stolen by clairvoyants and mediums every year, and I can prove it,” Houdini told the committee when he was able to speak. “Conan Doyle is the biggest dupe outside of Sir Oliver Lodge.” Houdini also took the opportunity to debunk palmistry and astrology.

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For Americans without the money or inclination to consult a professional medium, there was the Ouija board. A sort of do-it-yourself séance kit wherein the departed “guided” users to spell messages, Ouija boards had been around since 1890, according to the Talking Board Historical Society. But they saw a huge surge of interest in the years 1917 to 1922.

While many people considered the Ouija board a harmless toy, others saw something more menacing. Newspapers across the U.S. reported on obsessive users being committed to mental hospitals. (Not showing a great deal of empathy, the Philadelphia Evening Ledger headlined one article “Ouija Board Is Blamed for Increase in ‘Nut Crop.’”) The medical director of the New Jersey State Hospital for the Insane warned of potential overcrowding, adding that, “it would be difficult to imagine conditions more favorable for the development of psychosis than those furnished by the Ouija board and other mediums.”

Houdini, too, weighed in, calling the Ouija board “the first step towards insanity.”

Still, many Ouija board users claimed success in reaching dead loved ones. The Brooklyn Daily Eagle reported on a local woman who said she’d used a Ouija board to communicate with her late son, a sailor in the Navy whose ship had gone down. “He told me there was no suffering where he was, and that he was extremely happy and that his father also was happy,” she said. Her son also wanted to correct the historical record, she added; contrary to reports that his ship had been sunk by a torpedo from a U-boat, he told her, it had actually been bombed by a zeppelin.

The heightened interest in spiritualism in the U.S. continued throughout the 1920s and well into the 1930s, but dropped off with the coming of World War II in 1941.

In 1919, a New York Tribune writer tried to summarize what spiritualists claimed the dead had to say about the next world. “They tell us that dying is not a painful process,” he began, adding that it sometimes takes the recently deceased a while to realize that they are no longer among the living.

“Finally,” he concluded, “they all say that in no circumstances would they come back.”