«فِي لَيْلَةٍ أَدِيمُهَا ذُو لَوْنَيْنِ»
On a night whose outer skin seemed to have two colours.
The night is presented as though it has a two-coloured surface. Adīm literally denotes skin or surface, used figuratively of darkness and changing light.
The unexpected caller at a closed door creates suspense and puts hospitality to the test. The narrator withholds full motives until subsequent events unfold.