Warning! Spoilers ahead! I have not read the book series this show is based on, so this is a highly speculative review and summary

This episode continues the build up of the tension in silo18 towards rebellion, with an outright message to the rest of the silo via a launched rocket full of, albeit true, propaganda. The main story lines are the continuation of the pressure towards revolution and rebellion from the down deep mechanicals and the upper crust of the Silo, namely IT and Judicial. The other main story is Jules in Silo17 after being coerced to help Solo dives down into the lower levels to hook up power to the water pumps. She is successful but loses her rope connection to the above signal bell as well as the air being pumped to her. She rapidly ascends and looks for Solo, she puzzingly sees an axe presumably the one used to cut her rope and sees blood on a wagon. It appears there was a struggle and hence obliquely confirms they are not alone in silo17.

What makes this episode interesting is the side stories:

• Lukas is promoted to being the Head of IT Shadow which is super cool, but shows desperation on the part of Bernard to figure out Quinns code.  The legacy is revealed as well as what is behind the locked door -- it is gorgeous!
• The story of Camille Sims has been somewhat under the radar but suggests she may be on the side of the rebels and her rationalization is to be friendly with whichever side may win. However she has been helping the "Friends of the Silo" since season one.
• The relationship between Robert Sims and Bernard has deteriorated to the point of non-existence. However Sims is already showing he will not be a stooge to Bernard. Robert Sims takes his life into his own hands as Bernard has shown to murder people who stand up to him. As the relationship further deteriorates, Sims may side with the rebellion.
• The story of Sheriff Billings is interesting as he has always been a stand up law abiding citizen, even when in Judicial and having memorized the Pact forwards and backwards. He seems to be inadvertently siding with the Rebels just out of principle of not picking sides at all.
• The love story between Knox and Shirley. I think this has been somewhat controversial among the fan base, but it makes for an interesting twist even if whimsical...so far.
• The love story between Walker and Carla.  Could this spark a betrayal from Walker towards mechnical? Something is there to be exploited and it was found in the tapes where they were holding hands in the jail cell despite being divorced 25 years earlier.
• The relationship between Bernard and the deputies. They are following him for now, but at some point the truth will come out that Sheriff Billings is not saying things against his will.
• The existence of a listener network who gets their secret orders from IT is quite unsettling and is explored this episode with Miller being identified as a listener and Mauve as the person who poisoned the food who was threatened with withholding medications from her mother who is in the medical floor in order to get her to comply.

Salvador Quinns Code

As discovered in this episode, the Quinn Code appears to be a numeric cipher that points to pages in a book. He wanted his code to be solved so did not use any books in the Legacy as a key to his cipher.

The Wizard of Oz is a public domain book and can be found: https://www.gutenberg.org/files/43936/43936-h/43936-h.htm

If we are to start on page 77, it speaks of a Dorothy and her companions coming upon a fork in the road. If you extrapolate that to the people of the Silo, they are likely coming upon a fork in the road as well, whether to rebel or stay ignorant of "the truth" or whichever version of it that exists for the sake of peace an compliance.

Trivia and interesting tidbits

• The Legacy which strangely resembles the Medical Museum in Philadelphia comprises of the whole of human history and culture as contained in a tablet. The books and relics in the room behind the locked door are only a fraction.
• The AI computer refers to the rocket explosion-pamphlet releasing event as a Delta Event in the central shaft.
• The Silo was built 352 years ago. still unknown why it was built or why they are here.
• IT Lies to us. Mechanical wants THE TRUTH. What happened to Juliette? How did Meadows really die? What is IT hiding? Look and see.
  

The Bends

However, in the apparatus used by Jules, it is merely an air pump not a compressor and if it were a compressor they do not have a way to account for the changing pressure based on depth. Modern devices use the ideal gas equation (PV=nRT) to calculate this. So it is unlikely she would have the bends because she would not have the air delivered in a compressed fashion. However there is a very very small chance. Regardless, for the sake of the story, if she ends up battling "the bends," then so be it.​

​Pez dispenser

The Pez dispenser is symbolic of innocence. Thinking about what it is, a simple child's toy that gave candy, if anyone has one as a kid it hopefully reminds you of a good childhood. In the Silo, it is a banned relic and whoever holds it seems to be pretty innocent about everything going on in the Silo but perhaps about to find out more. It's appearance in the hands of Robert Sims's son is telling of his innocence, but it could it be foreshadowing of his loss of innocence as it has been for George Wilkins and Juliette Nichols.

​George Wilkins

As these episodes go by, I can not help but think how useless the death of Jules's love interest was. It certainly helped push the story forward but in terms of what he died for, the survival of the hard drive and to protect Jules. None of which really happened. In a way it happened anyways as seems to be the natural course of events in the Silo. But it seems his death along with the other lovable characters from the early episodes, Sheriff Holston and wife, Mayor Jahns, Deputy Marnes were truly tragic.

​Characters of interest this episode

Bernard Holland - Going through an incredible amount of stress as he deals with the politics in the Silo in addition to creating a potential rebellion so that he can crush it as dictated by the Order.
Camille Sims - supports the rebels, albeit secretly, as she attempts to convince Rob Sims from going to talk to Bernard. The only time she shows him a large amount of affection in both series is in this scene.
Robert Sims - really goes on a limb to argue and push back with Bernard Holland, he is almost forced to befriend the brewing rebellion.
Knox - The co-leader of the rebellion and very persuasive to the mechanicals
Shirley Campbell - The co-leader of the rebellion also persuasive but not as much as Knox. The potential love interest for Knox.
Carla McLain - Currently being held by Judicial/IT.
Walker - love interest of Carla and holds lots of credibility among mechanical. Feels she needs to do "something more" to save Carla and in so stating, reveals a huge regretful burden she's been carrying for years.

​Unanswered questions

• ​Who is Salvador Quinn and what is the significance of his letter? It must be important for Judge Meadows to mention it and say she cant tell him and for half of it to be in code.
• The display showing the illusionary perfect world died as Jules walked a certain distance but Bernard was still able to see what she saw. How come? The assumption was the wifi signal was too weak. It could be the video as made for the display simply did not take into account a person would go that far and past the simulation.
• How long has Silo17 been dead?
• Did someone cut the rope from Episode 1? If so, it likely wasn't Solo, he could barely walk across the platform. Who was it?
• Dr. Nichols will likely be caught, since he is being watched so closely. What purpose does this serve for the plot? He seems to be in a dont care or under the radar point of view at the moment, but he keeps being put in some questionable situations, now in the down deep.
• Who is part of the ring of people that hacks the Silo's security network? It appears its just a large amount of normal citizenry that are intentionally breaking the cameras.
• Who was helping Jules escape by turning off the cameras at key opportune moments?
• What is the syndrome?

Review of previous episodes:
Season 1

Season 2 Episode 1 - The Engineer
Season 2 Episode 2 - Order
Season 2 Episode 3 - Solo
Season 2 Episode 4 - Harmonium
Season 2 Episode 5 - Descent
Season 2 Episode 6 - Barricades
Season 2 Episode 7 - The Dive
Season 2 Episode 8 - The Book of Quinn