An actual MacGuffin!

Production-made printed maps for Steven Spielberg's action adventure sequel 'Indiana Jones and the Last Crusade'. Indiana Jones (Harrison Ford) used his father's (Sean Connery) diary to find his father and eventually the Holy Grail itself.

The third film, 1989's 'Indiana Jones and the Last Crusade', set in 1938, returned to the formula of the original, reintroducing characters such as Sallah and Marcus Brody, a scene from Professor Jones's classroom (he now teaches at Barnett College), the globe-trotting element of multiple locations, and the return of the infamous Nazi mystics, this time trying to find the Holy Grail. The film's introduction, set in 1912, provided some backstory to the character, specifically the origin of his fear of snakes, his use of a bullwhip, the scar on his chin, and his hat; the film's epilogue also reveals that "Indiana" is not Jones's first name, but a nickname he took from the family dog. The film was a buddy movie of sorts, teaming Indiana with his father, Henry Jones, Sr., often to comical effect. Although Lucas intended to make five Indiana Jones films, 'Indiana Jones and the Last Crusade' was the last for over 18 years, as he could not think of a good plot element to drive the next instalment.