The Crown of the Crusader Kings

The Crown of the Crusader Kings is a Scrooge McDuck comic by Don Rosa.

Plot
Scrooge McDuck is searching for the crusader kings' crown, and the International Money Council in Paris is after it too. The International Money Council claims to have rightful claim to the crown, as its tradition continues directly from the Knights Templar. The crown became their property on October 13, 1582, 100 years after they had lent it to the Spanish and Portuguese kingdoms. The Ducks manage to prove that because of the switch to the Gregorian calendar, there never was an October 13 1582, and so the crown was never returned to the Knights Templar. At the same time, Donald Duck also proves that Friday the 13th never happened either. However, the government of Haiti is recognised as the rightful owner of the crown, as it was found on their property. Scrooge is satisfied by keeping the fabric on which the crown was wrapped in as it is the Clan McDuck tartan, indicating the knights Templar's treasure is located in the castle McDuck.

The story continues in ''The Old Castle's Other Secret or A Letter From Home.

Some references indicate this as a follow-up to Return to Xanadu, which happens to be a sequel to both Tralla La and The Lost Crown of Genghis Khan.