There are probably fewer things more awkward for an adulterous husband than insisting to your suspicious wife that you are not having an affair only to have your mother-in-law spot your mistress someplace she shouldn’t be.

For Harrison G. Dyar, that someplace was Pasadena, Calif.

At least, I think it was. More than a century after the events in question, it’s hard to be sure who knew what about whom when in the messy triangle that was Dyar; his wife, Zella; and his mistress, Wellesca Pollock. At times, my brain would ache as I spread newspaper clippings, trial transcripts and real estate records out in front of me and tried to reconstruct the affair.

Dyar became famous in Washington for the elaborate tunnels he dug under his home early in the 20th century. His private life was just as convoluted a construction.

This much I do know: The mistress was no stranger to the wife. The Dyars were regular guests at Skyland, the Blue Ridge resort run by Wellesca’s brother, George Freeman Pollock. Zella crossed paths with Wellesca in Washington, too, where Wellesca was an unmarried kindergarten teacher. Wellesca’s embrace of the Bahai religion must have resonated with Zella, whose mother, Harriet Peabody, was a Bahai.

And so it is that we find ourselves in the summer of 1906 in California. Dyar’s family — his wife, their children Dorothy and Otis, his mother-in-law — have gone to Los Angeles. Dyar has followed, then gone to the Grand Canyon to collect specimens. I’m sure he did collect specimens. He also collected Wellesca, who met him in Arizona. The lovers are able to spend several days together amid the grandeur of the desert cliffs.

Dyar returns to Los Angeles. Wellesca, instead of returning to Washington, goes to Pasadena. Perhaps she’s hoping to see Dyar again. Perhaps they’ve even planned it. What they surely didn’t expect was that Zella’s mother would go to Pasadena one day and spot Wellesca there. Harriet returns home and shares the news with her daughter and son-in-law.

Dyar acts surprised. Really? he says. Miss Pollock in Pasadena? What a coincidence.

I’m sure that at this point, Dyar and Wellesca have been sleeping together for a while. Maybe Zella has been suspicious from the start. Maybe getting her husband out of Washington was a way to get him away from temptation. Maybe this hasn’t worked.

On her long train ride back East, Wellesca has time to contemplate something that happened on the trip out West. While waiting to change trains in Chicago, she had struck up a conversation with a man named Wilfred Allen, who told her that he was a railroad conductor from Pittsburgh. Wellesca, in the way of religious converts everywhere, is eager to share the story of her newfound faith and tells Allen about it. She takes his address and promises to mail him literature.

This she does. Then Allen mails her something: a marriage proposal.

If it seems odd that Wellesca would consider marrying a man she spent an hour with between trains, you’re probably right. But Wellesca accepts. On Sept. 5, 1906, she and Wilfred Allen sign a marriage license in Richmond. Perhaps being Mrs. Allen will put an end to the hateful gossip about her and Dyar.

But Mr. Allen doesn’t have much time to see Mrs. Allen. No sooner are they wed than he takes a job with a wealthy but reclusive Philadelphia man named Mr. McGrath. Allen tells Wellesca that certain complications early in his life have made it necessary for him to adopt an assumed name. He instructs her to send him correspondence in care of “General Delivery.” Wilfred Allen will never meet Wellesca’s family, and he will see her just three times over the next seven years. Nine months after each of those visits, Wellesca will give birth to a son.

Meanwhile, some time during 1906 — or maybe a year earlier — Zella decides she wants a vegetable garden and a bed of hollyhocks in the yard behind the Dyar house at 1512 21st St. NW.

“You know the hollyhock grows best if the earth under it for many feet is loosened,” Dyar later tells a reporter. “The roots of the hollyhock penetrate very deep into the ground. Well, I volunteered to dig the garden. When I was down perhaps six or seven feet, surrounded only by the damp brown walls of old Mother Earth, I was seized with an undeniable fancy to keep on going.”

And that’s exactly what he does.