Mozart's C Minor Mass (K.427), widely known as the Grand Mass, is far more ambitious and elaborate than even his magnificent Requiem Mass (K.626). In retrospect, perhaps it helps not to perish in the process...but we digress.

The Grand Mass is heard less often than the Requiem (no less than 118 years passed between its first performance and the second). And the story behind it has been eclipsed by far lesser dramas.

This brilliant masterpiece was initially performed by the Hudson Valley Singers, under the baton of Eugene Sirotkine, on January 19, 2003. That performance featured soloists from the Metropolitan Opera Chorus and the New York Metamophoses Orchestra.

In the summer of 2007, Mr. Sirotkine and members of the HVS chorus performed the C Minor Mass in Budapest, at the 700 year-old Mátyás-templom and at The Franz Liszt Academy of Music.

Although the Grand Mass itself is less well known, even fewer people know the intriguing story behind its creation and first performance. "Amadeus" was quite an entertaining film and play, but the real story is considerably more compelling.

Yet for all its polyphonic grandeur, the coming of the C Minor Mass gives us a chance for some genuinely Wolfganian fun. So we created a little game we call "C Minor Mastery," in which you get the chance to lord your superior knowledge and intellect over everyone else. Leopold, we fear, would never have approved - not openly, anyway.

Then apply your deductive powers to come up with your solution to the C Minor Mystery.