“You should go to the block on Tulskaya Ulitsa, just by the bridge,” Raisa told her. “My husband and I used to live there and it was full to the brim of displaced people searching for their families, poor things. I think the authorities put them there as a temporary measure in the hope that they will find relatives and not need rehousing after all.”

As soon as she mentioned it, the idea took root in Maria’s mind: if she heard of such a place, Tatiana might go there to search for her. It was silly, she knew, and she decided not to tell Peter, but to Raisa she said, “I’d love to help if I can. Perhaps you and I could go together and you could introduce me to some of your old neighbors.”

Raisa liked the thought of any venture that let her snoop on other people’s lives, so one day in the spring of 1924, just after the snow had melted, they went together to the block in question, Stepan and Irina in tow. Raisa knocked on doors, introducing Maria and explaining that she had a talent for reuniting families. Maria had brought a notebook in which she took down their current addresses and drew quick sketches to act as an aide-mémoire. Although she knew it was almost certainly futile, she peered through doorways hoping to catch a glimpse of Tatiana, but with no luck.

One woman brought a boy of around six to her door. “I have not seen his father since 1918,” she said, “but he is the spitting image of this little one. Will you look for him on your travels and ask him to bring me money to raise his son?”

As Maria took down their details, she kept glancing at the woman. There was something about her greenish-hazel eyes that seemed familiar. “Do you by any chance have a sister called Nadezdha?” she asked.

The woman’s eyes widened. “How do you know her? When last I heard, she was in Moscow.”

“Not anymore.” Maria smiled, copying out the address of one of the women she had promised to help. It turned out to be her second successful reunion, and she was proud of that.

When she finally told Peter about her unofficial missing-persons bureau, he was concerned. “Maybe it is not a good idea to draw attention to yourself in this way. The more new people you meet, the more likely you are to be recognized as a Romanov.”