I HEARD THE bare bones of this story during the war, soon after it happened, and I mentioned it briefly in my book The Shetland Bus. All that I knew about it then was based on a report which was written in a Swedish hospital by a man called Jan Baalsrud. It was a graphic report, but Baalsrud was very ill when he wrote it, and it left a lot unsaid. One could see that there was much more in the story, some things which Baalsrud had forgotten and others he had never known, although he played the main part in it. But it was not until ten years later that I had a chance to talk it over with him, and persuade him to come with me to the far north of Norway where it happened, to try to find out the whole truth of it.
Now that I have found it out and written it down, I am rather afraid of being accused of exaggeration. Parts of it are difficult to believe. But I have seen nearly all the places which are mentioned in this book, and met nearly all the people. Not one of the people knew the whole story, but each of them had a most vivid recollection of his own part in it. Each of their individual stories fit together, and also confirm what Baalsrud himself remembered. Some minor events are matters of deduction, but none of it is imaginary. Here and there I have altered a name or an unimportant detail to avoid offending people; but otherwise, I am convinced that this account is true.