In some time travel stories the traveler can control his departure and arrival quite accurately, but in this story, Robert doesn't understand how he comes to be in Siberia and settles down into a dreary, poverty-stricken life there. He thinks he is marooned, out of his own time and place. He is taken in by Olga, a Russian pharmacy attendant and stays in her impoverished flat with communal kitchen. Robert has a series of seven adventures in outlandish, rather unreal places and time zones, always drifting backwards in time. He spends many months in each place, resigned to the fact that he cannot escape.
Some themes run through the whole book.
For instance, the collection of junky bits and pieces which Robert carries with him in his jacket pocket from time zone to time zone, both benefit him in his travels and incriminate him. Gradually, he loses them all along the way, leaving his twentieth-century junk scattered through time like derelict satellites orbiting the earth. But he does manage to bring one thing back with him from 1621, when he finally returns to his own kitchen, a couple of years after his journey began. Well, he must have been somewhere because he brings back the paintbrush, to prove it. So it wasn't all just a bad dream.