A Letter From Home or The Old Castle's Other Secret is a story written and drawn by Don Rosa. It features Scrooge McDuck, Donald Duck, Huey, Dewey and Louie, monsieur Molay, Maurice Mattressface, Matilda McDuck and in flashback, Simon McDuck, Hortense McDuck, Fergus McDuck, Downy O'Drake, Angus McDuck, Theodore Roosevelt, Della Duck and Quackmore Duck.
In their quest for the treasure of the Knights Templar, Scrooge McDuck and his nephews Donald, Huey, Dewey and Louie Duck travel to Castle McDuck in Scotland. There, Scrooge is reunited with his sister, Matilda, though she doesn't seem to have yet forgiven him for the greed and coldness which defined him almost 25 years ago. Monsieur Molay and Maurice Mattressface are after the treasure too, and Molay won't stop at anything to get it.
- This story forms the second half of a story arc, with the first half being The Crown of the Crusader Kings (2001). The titular crown, according to legend, was supposed to be part of the the Treasure of Knights Templar, but Don Rosa preferred to have its discovery be a step on the way to the real treasure.
- Don Rosa also used this treasure hunt as a reason to tell a story about a return to Castle McDuck, a follow-up to one of a younger Don Rosa's absolute favorite Carl Barks adventures : The Old Castle's Secret (1948). However, he later reflected that his version failed to live up to the Barksian original: Barks "delivered the goods" of his title with action and intrigue in every nook and cranny of a huge castle, whereas most of the "screentime" of Don Rosa's Other Secret is taken up either by the familial drama, or by a treasure hunt underneath Castle McDuck.
- Even though Scrooge McDuck needed some treasure hunt that would lure him back to the Castle McDuck the main purpose of Don Rosa in this story would not be that quest, it would be somehow deal with Scrooge's relationship with his departed parents and with his sisters Matilda and Hortense McDuck, whom he had established Chapter 11 of his Life and Times of Scrooge McDuck,The Empire-Builder from Calisota (1994), as having become estranged from the tycoon.
- Don Rosa had also established a version of the McDuck coat of arms in the Life and Times of Scrooge McDuck's first chapter, The Last of the Clan McDuck (1992). Though a McDuck Coat of Arms once again appears in this story, he decided to rework it from scratch to accord better with historical heraldry.
Don Rosa is well documented write his story. He often said that for the work of documentation for this history was the larges the had done. All the informations that he uses in this story are true, Scotland is where many historians believe the Templars fled with their treasury, and the Templar banking cipher that is the basis for his treasure hunt is the actual secret code they used according to the myths. The only fact that he made up is that which tells of a certain Clan McDuck and their ancestral castle being involved. We can also mention that the "priory of Zion" which is quoted in numerous books of stories was revealed like being a hoax.
The Knights Templar are a a major element of this story-and another had already revealed that Scrooge had an ancestor in the Order, Sir Simon McDuck. To create the treasure that Scrooge finds at the end of the story, Don Rosa followed the legends and history of the Knights Templar, weaving fact and fiction. It is true that these warrior monks were some of the most capable fighters, sailors, builders, scholars and bankers of the Middle Ages; it is often said that the Templars discovered and looted the ancient treasure vaults below the Temple of King Solomon in Jerusalem; tis Don Rosa was able to add mythical objects such as the Ark of the Covenant and the Holy Grail to the gold and gems of his take on the legendary treasure.
Whitin Don Rosa's oeuvre
Don Rosa searched for a long time to find the plot of this story; he needed to find a treasure hunt that would be wholly original for Scrooge McDuck. Scrooge had already found many treasures through the many treasure-hunting Scrooge stories. Which remained? The Lost Gold of the Incan Empire, that'd have been a whopper, but Don Rosa had already written it as his first story, The Son of the Sun. The treasure of Eldorado would have been an even greater hoard, but Rosa had already created The Last Lord of Eldorado. How about the accumulated knowledge of every ancient culture, from Rome to Cathay, that was lost when the Library of Alexandria disappeared ? Guardians of the Lost Library had already filled that gap. Hence did Don Rosa come to land on the treasure of the Knights Templars as one of the last grand, legendary historical treasures left for Scrooge to find at least as far as his Barks's stories were concerned.
Despite many requests from fans, Don Rosa knew that he could not theme a Scrooge treasure hunt around the search for holy items because he should be talking about the religion and his stories are areligeous. But, he realised that the Grail (and the Ark of the Convenant) were only one part of a larger treasure that Scrooge was already seeking. He could send Scrooge in the search of the Grail and not be forced to specifically explain the Grail's significance.