Having survived being poisoned, tonight's episode of 'Da Vinci's Demons' has Da Vinci and the gang going into the vault of heaven, only to be faced with a series of tests, though fortunately there's no old knight waiting for them at the end.

The episode starts with Riario mourning the loss of his girlfriend (you know, the one he killed in the last episode) as Leonardo, Zoroaster and Nico look on. Da Vinci feels exceptionally motivated to get the book, so Ima tells Leonardo the two are ready to enter the vault of heaven, but when Riario protests, it turns out the whole crew can enter the vault, proving once and for all it wasn't a metaphor for doing it.

Back in Florence, Clarice is going at it some more with Carlo, but post-coital pillow talk devolves into Carlo fearing that he'll be killed for their indiscretions and/or that she'll pretend it never happened (and Laura Pulver seems to be getting some old school glamor lighting here as she looks borderline photoshopped), but then a ninja assassin breaks in through the roof! A ninja! Carlo takes one out, and then finds another assassin in Vanessa's room and kills that one too. Dragonetti reveals the killers were seemingly sent by Duke Frederico. Carlo confronts one of the bankers, because he thinks Frederico wouldn't be so sly, and when the banker reveals his role in the attempt, this leads Clarice to act more lovey-dovey with him in public, which makes him nervous.

In Constantinople, the son of the sultan puts a boy into the army as Lucrezia shows up. She brings him the sword of Osmond, which grants her an audience, but he ends up keeping her locked up as he goes off to fight. At the Vatican, Lupo researches the book of leaves, but the fake pope acts like a jerk about it. Lupo goes to talk to the real Sixtus who says they'll need a man of action. Lupo then breaks into the vault and sees a map to the vault of heaven.

In the new world, the vault of heaven proves to be filled with tests (you know, like 'Indiana Jones and the Last Crusade'), with the first being a booby-trapped floor. Leonardo builds a "scorpion" and is able to get past it. The next test involves crossing over a bottomless pit and inserting a key into a hidden keyhole. Leonardo almost fails the test, so he's separated from Ima. The next test involves a disco ball and another keyhole, which leads Riario to pull a knife on Zoroaster when he's questioned for thinking this test would be easy. It turns out that the disco ball is the key as light has to shine on the door when they turn the keys. Nico and Zoroaster get stuck manning the doors while Leonardo and Riario go in, but then Ima shows up and has her guards take them prisoner. It turns out Ima was just using them to get the book for herself. But the big shocker is that Leonardo's mom is also in the vault.

Tonight's action-heavy episode left Lorenzo out of the mix, which is fair enough, and turned out to be a middle episode that mostly functioned to set up the home stretch of the second season. The biggest problem with the episode is that the Clarice and Carlo relationship is a non-starter. One has empathy for both performers, but their relationship seems more plot-driven than organic -- though it's easy to understand how Clarice could need some sexual attention (seeing as how her husband spent the first season fooling around with Lucrezia).

The puzzle stuff with Da Vinci was fun, though the problems he solved didn't show exactly how he figured it out (if you can go "a ha!" along with the character, it's always more entertaining), while the other plots were mostly about getting things into place. Tom Riley is the star of the show, and he got to have fun this week, which made this mostly enjoyable. But as the show is modeled on serials, this chapter was more about getting to the next one than about the thing itself.