After a week off, 'Da Vinci's Demons' returns with only two hours left in its first season. There's been a lot set up at this point -- and we got to meet Dracula -- but now is the time for all the big plot points to come into focus. At least, we hope.

The episode opens on Da Vinci spying on Girolamo Riario in a pauper's graveyard. The grave Riario visits is of a Jewish woman, while Leonardo plots to raid the Vatican's secret archives. Back in Florence, Lorenzo plots to marry Giuliano to Francesco Pazzi's daughter, and it's revealed that Lorenzo hasn't told his brother yet about the marriage. Lorenzo breaks the news to his brother while practicing archery, and Giuliano resents him for it.

Leonardo smokes some opium and sees a vision of Lucrezia who tells him that she loves him, but when he can't say it back, she stabs him. Leonardo then wakes up. He dunks his head underwater, and figures out how to sneak in by making a diving suit. Cut to: Days later, and Da Vinci is in a boat about to test his underwater gear. At the bar, Giuliano is getting deeply drunk when the last call bell is rung. Vanessa flirts with Giuliano, and the two go to her place to have sex. The next morning Vanessa brings Giuliano a hangover cure, and when he brings up that he's betrothed, she says she would rather they not fall in love as she doesn't want to be royalty. He's reticent to marry because he thinks the Pazzis set up Bechhi, and Vanessa urges him to find out the truth.

Da Vinci has made it under the vaults and starts drilling, while the Pope meets with Riario and the Duke of Urbino, who last week signed up with the Medicis. Riario attempts to raise the Duke's rates, which offends the man, while the Pope suggests they meet a little later to talk it over. Giuliano finally gets the secret files from Captain Dragonetti, and finds that Lucrezia is out late at night. Giuliano thinks that she's the spy, and goes to find and question her.

Francesco Pazzi meets with some conspirators and Captain Dragonetti to discuss saving their city and killing the Medici brothers. Da Vinci is drilling and finally breaks through, which the Pope notices as he's about to take a bath. Da Vinci rises in slow motion and confronts the Pope. He asks to see the secret archives, and the Pope says he'll lead him to it, but Leonardo smells a trap. He then finds a secret passageway himself. Francesco reveals that the Giuliano marriage is a sham, and plans to kill both brothers and have Dragonetti take over. One conspirator argues about how the takeover will go, but he's then poisoned, and Francesco uses it as a way to show how serious he is about taking over. Giuliano shows up at Ana Donati's house, but she says Lucrezia took off days ago. Leonard finds the secret archives and argues with the Pope, who then offers Da Vinci a position as the explorer of the archives, which has its own elevator. Giuliano plans to follow a road where he thinks Lucrezia would go if she was a conspirator, but it turns out that Lucrezia was still at Ana's, and plots to work with Leonardo to get out of her situation.

The Pope shows Leonardo a dragon's head, glowing crystals, Excalibur, and the Spear of Destiny, which he hands Leonardo. But what he doesn't show Leonardo is the key. The Pope then brings up Da Vinci's mother, and says he can reunite them. Then Riario and the Duke of Urbino enter the bath, and draw their weapons and sound the alarm when they see Da Vinci's handiwork. The Pope suggests everything could be at Leonardo's disposal if he aligns with Rome. He also shows Leonardo a page from the book of leaves, and it features a language Da Vinci's never encountered. It also changes text when light is waved in front of it. The Pope says the book contains secrets from the divine. Just then guards start to come in, and Leonardo fights his way out. A diving suit emerges from the water, but it's Riario, and he and Zoroaster fight until Nico knocks Riario out.

Da Vinci runs into a guard that has the upper hand, but Leonardo's weapon -- the Spear of Destiny -- cuts through armor like butter. Back at their campsite, Nico wakes Riario and gives him a scar. Riario can't help but provoke Nico, and so Nico stabs him in the hand. But when Nico goes for the kill, his blade is blocked by the second key. Leonardo prepares to lower himself out a window when he hears someone humming. It's a tune he's heard from Lucrezia, and he confronts the man humming it. The man says he invented the song. It's Lucrezia's father. Leonardo shows the man Lucrezia's ring, and the father asks if Leonardo loves her. Leonardo feels that meeting her father unlocks her for him, and figures out that she's the spy. Leonardo unlocks the father's cell, but the father says he's exactly where he needs to be. Da Vinci then escapes on his own.

Leonardo shows up at Nico and Zoroaster's campsite. Da Vinci says he didn't find the key when Zoroaster reveals their success, and Riario. Da Vinci leaves Riario tied to a tree, but Riario threatens to kill the person Leonardo loves most. On the road, Lucrezia hides as a leper, but three of Rome's men can tell it's her, and plan to rape and kill her. Then Giuliano and his squire show up. The three reveal that she spied for Riario, but then she runs off and the men fight. Giuliano kills the three, but loses his squire. Giuliano then confronts and captures Lucrezia when she stabs and kills him. The camera then circles her and Giuliano's body drifts off down a river.

Okay, stakes raised. Though not killing Riario is nice for the show because of Blake Ritson's deliciously evil performance, Giuliano is the first of the regular cast to be killed off, and it was a total surprise. It's also terrible, yet ironic, that Giuliano figured out the whole spy thing and was proved right, only to die shortly thereafter. And with shows like this, it's worth noting that his death was in no way telegraphed. There was nothing that has happened to this point that made him seem like someone who could die, and until it happened, it didn't seem likely, even if Lucrezia was in a corner. Bravo for that.

There was some fun plotting in the earlier part of the episode, but the show seems to have broken from its original formula of having Da Vinci solving a puzzle every week, and that's good to know as we head into the end of the season. With assassination attempts, a key obtained, and Lucrezia on the run to destinations unknown, there's a lot that could happen in next week's finale, and we can't wait. But we will, because we have to.