Ok here is the claimed sequence of events:
Prologue: An old German on a hospital in Munchen approaches an Icelandic medical student which was there, and tells him the rough story. He sais "this is a part of your nation's history, and it must be allright if I tell you after such a long time". The German died soon after.
The trip:
Takeoff from Sola airfield near lunchtime on the 19th of March 1941 in a long-range He111 (12 hrs).
Crew of 4, Holle, Canaris, the navigator and the radio operator.
The aircraft gets hit by flak over Reykjavik and crash-lands at roughly 4:15 which I presume is 16:15 which gives it some 4-5 hrs of flight time on the rough 1000 km leg. Would that fit? Guess so.
The crew torched the aircraft.
A message is sent to a "contact" in Hella, a town some 60 miles further to the east, as well as to a hip in the harbour of Heymaey, an island of the south coast.
One crewmember gets injured, so they split up. 2 of them head for Reykjavik (with the injured one), while the other 2 (Holle & Canaris) head straight east for a long walk.
The former were spirited on board a ship in Reykjavik harbour, while the latter were picked up by a "friendly" and driven & walked to Hella. (The British had sentries on some bridges, but showing papers was not mandatory). It takes them 4 days to reach the southern coast, where they stal a bot and make it to the ship.
The ships in question were namedMS Edda and S/S Spica, codenamed Juan Fernandes/Shiff 28. That one sailed to Reykjavik, where the crew unites on board M/S Edda. The author claims he has a witness who saw the transfer.
Edda departs for Spain (fish export). It gets stopped by the submarine U-98, which takes the fugitives to France. 23 days had passed. (U-98 was actually landing in France on the 14th of April, so the time and location fits)
Further claims:
Holle had 2 long-ranged He-111 at his disposal.
The wreck was swiftly removed by the Reykjavik chief of police. Now there was a character worthy of a riddle, and he later claimed that if he was to open up about police ops in Reykjavik in the war-years, it would be on par with the finest Bond stories. I have been reading into operations right before the outbreak of the war, and it is already quite something!!!!
There are many missing parts here, but something to start with. Holle's location and time of death fit. He did have at least one He-111 at his disposal. The ships involved did carry the codenames he wrote down for the baffled young Icelander. Some ships did have "deals" with the German subs. Oh, and Heinkels came here on frequent occations for Recce (convoys) and that is exactly what Holle got involved with. Some of those got shot up, or perished for other reasons, but the loss reports are very foggy. There are still un-identified wrecks in many locations of the country.
The famous PQ-17 sailed from "Hvalfjörður, Iceland" and was later attacked by Holle's bombers, the recce part was about logging in the date of departure and preferably convoy size.
But what the devil was Canaris doing? This is a very risky mission for the head of the secret service! However, he had turned his back on Hitler....