This episode is set sometime during the second half of World War II. When Nisse Fisk gives Erik a can of caviar to deliver, he says he got the can in the spring of 1939 and that he has been saving it for five years. This would indicate that the episode is set in early 1944 (and indeed, there is a lot of snow outdoors, indicating that it is winter). During the same day, when Kettil Kyhle goes to see the pawn-broker, we get an exact confirmation of the date from a calendar hanging on the wall in the pawn-broker's office. It says it's 24 February. However, it also says it's a Tuesday, but in 1944, 24 February fell on a Thursday. The only year during World War II when 24 February fell on a Tuesday was in 1942.