Short answers, pulled from the story.
The Northern Isles are located off the north coast of the Scottish mainland and consist of two main archipelagos: Orkney, which lies 16 km north of Scotland across the Pentland Firth, and Shetland, which sits around 170 km north of mainland Scotland. Together they contain 36 inhabited islands.
The Heart of Neolithic Orkney is a UNESCO World Heritage Site designated in 1999. It comprises four prehistoric monuments: Skara Brae, Maes Howe, the Stones of Stenness, and the Ring of Brodgar.
The Northern Isles were formally annexed to Scotland in 1471. In 1468, Christian I of Norway pledged Shetland as security for an unpaid royal dowry; the money was never paid. In 1470, William Sinclair, 1st Earl of Caithness, ceded his title to James III, and the annexation followed the next year.
The Shetland Bus was a Norwegian naval unit established by the Special Operations Executive in the autumn of 1940, based first at Lunna and later at Scalloway in Shetland. Using about 30 fishing vessels gathered from Norwegian refugees, it made over 200 covert crossings to occupied Norway, carrying agents, resistance instructors, and military supplies. Leif Larsen, the most highly decorated Allied naval officer of the war, personally made 52 of those trips.
After the Armistice in 1918, the entire German High Seas Fleet was transferred to Scapa Flow while its fate was being decided. German sailors resolved the situation by opening the sea-cocks and scuttling all of the ships.
Norn was spoken in the Northern Isles before Scots gradually replaced it. Norn descended from the Old Norse brought by the Vikings in the 9th century and began fading after Orkney and Shetland were absorbed into Scotland from 1468-1469. It became extinct around 1850, following the death of its last known speaker, Walter Sutherland.