Something I find very interesting about the adaptation of The Expanse from novel to TV is how the TV show added a lot more mysteries and hidden information for the characters based on things that were instantly talked about in the books.
Bobbie’s encounter with the Project Caliban protomolecule monster on Ganymede, for example. In the books when she’s being question by her superiors after the event one of the first things she says is that there was some sort of monster there that attacked her troops and the UN forces both. When her superiors are skeptical she tells them how to access her suit’s camera footage, they do so, and in the same conversation they come back and apologize for doubting her and they all say “What the fuck is this?”
In the TV series, she’s so disoriented and traumatized that it takes days and multiple interrogation sessions (Plus mind-enhancing drugs) before she can remember the events, and her superiors instantly dismiss the story and order her not to mention this to anybody because they’re part of the cover-up conspiracy. Her suit’s video footage is unrecoverable (Whether it’s actually damaged or is being suppressed it not made clear). She has to defy orders and defect to the UN in order to investigate what really happened.
Or Holden seeing Ghost!Miller. In the TV series he spends episodes keeping it quiet, not wanting to be thought of as insane or hallucinating. In the books he apparently told his crew the details as soon as it started happening, and he is also quick to tell everybody else as well when he needs to explain where he got certain information.
These aren’t mysteries for the audience, but the characters are kept in the dark for a lot longer.