Opera was invented at the beginning of the Baroque period, around 1600, but the first flowering of indisputably great works came with Mozart. He composed about a dozen, but there are four that are absolutely crucial: The Marriage of Figaro, Don Giovanni, Cosi fan tutte, and The Magic Flute.
Don Giovanni is another name for Don Juan, the legendary figure who sought to seduce as many women as possible, often through trickery. This telling of the story has many resonances with the present, with the intersection of class, power, and sex playing out in an often gleefully ironic manner. Don Giovanni, is, of course, a great villain, but he is also, in a way, the hero of the work.
His foil throughout is his somewhat unfaithful servant Leporello, who enables much of the shenanigans but also complains and cracks wise about both his employer and his female conquests. The “Catalogue Aria” is a famous scene in which he explains his boss’s modus operandi:
Here is a scene in which Don Giovanni attempts to woo a woman by performing a serenade outside her window.
Early in the first act he kills someone, and this is eventually his undoing, as the ghost of his victim appears and drags him down to hell. Giovanni redeems himself somewhat by going out with dignity.
The best introduction to this work would certainly be total immersion in a live performance with supertitles. Barring that, your next best option is probably to watch it on video. This Met Opera performance from 2000 with Bryn Terfel is probably a solid bet (and it is the source of the second clip, above.) You could rent it on netflix. Perhaps after viewing a fairly straightforward production, Peter Sellers’ wacked-out version might be a stimulating contrast. (Do NOT choose this one first, though. It would be confusing.)
For a recording, I have a 1961 recording led by Carlo Maria Giulini that is considered classic. While lacking the opulent digital clarity of a more contemporary recording, it still sounds excellent, and it is quite educational to hear the stars of a different generation perform this with verve.
(Important note: These links all lead to the 1987 remastering. Amazon reviewers complain bitterly about later editions that allegedly ruined the sound quality of this recording.)
There are, of course, many other recorded versions out there and I’m sure some are great. The Wikipedia page has a good synopsis of the action, so you could follow along even without the libretto.