I am pasting my answer to a comment when I tried to summarize the drama ep 1 to 31. In case it helps.

https://mydramalist.com/761587-zhang-le-qu#comment-18771897


Roxy     17 hours ago 

I've been watching this half-heartedly because I don't really understand what's happening with all the conspiracies. Why does Lai Luo Zhi want the throne? What is his family background? What is up with the Princess of Valor, is she in cahoots with him? Who is her daughter's father? The only plotline I understand clearly is that the Prime Minister and Prince Xian are working together to make him Prince Regent.


unbeliebubble     14 hours ago 

If I sum up  well:
The crown prince died long ago after, the Crown princess Ru Ning, at the time, wore a scandalous pattern on her summer gown. (embroidery fabrik investigation) After that, the Dowager became the Regent and put his son on the throne as the young Emperor.
His brother (Prince Xian) and his sister (princess Yong'an) became "wise king" and " king of england". In fact, they became King & king because they were from a previous dynasty, so the title were bestowed to them.
It is possible/logical that Prince Xian And Princess Yong'an conspired to kill their brother and take the throne. We don't know yet.

What we know is that Prince Xian is linked to VM Lai Luo Shi, who is linked to Governor of Yingzhou  MrMo.
After Gov. Mo died we learned that Prince Xian was in contact with foreign authorities and Princess Yong'an gave money to fund a rebellious army, also that the Zhou family was responsible for the arson of the granary Shen Du's father was accused of [thanks to the booklet + tribe's saintest assistant testimony].
This is why they tried to stop Shen Du/YanXing 's investigation multiple times.
As they failed Princess Yong'an bestowed her daugther in marriage on Shen Du, thus making him her son in law, thus stopping him from publically accusing her of high treason .
But Shen Du did not accept the Dowager's Marriage decree.( Maybe the Dowager is aware of all that) So, (to save her favourite daughter) the Dowager is now stripping Shen Du of his power and prestige and she gives her favor to VM Lai Luo Zhi.
As soon as it happened, VM Lai took all the cases. He immediately, jailed marshal Tan and the ministers to let Yingzhou unattended. And he flooded the capital with refugees in order to start the rebellion they planned long ago.

All of this is linked to Shen Du's father high treason case. He was accused of  :
- Communication with a foreign country. ( letter forged by the imperial teacher => cold case)
- Arson of the state granary. ( we know now that VM Lai stole the tribe saintest's fire technic to fake the arson and he stole the grain)
- Plotting a rebellion by owning a rebellious army.  ( we know now that Princess Yong'an funded this rebellious army )
- High Treason. (we don't know yet who is the final mastermind behind all this. Would it be Prince Xian? But they all participated in high treason, so they all are guilty)

=> Shen Du and Yan Xing are investigating to clear Shen Du's father name.

Why does Lai Luo Zhi want the throne?
I don't think he wants the throne because he is a noble not a royal, so logically he cannot access the throne. He works for Prince Xian.

What is up with the Princess of Valor, is she in cahoots with him?
The two Kings work against each other due to the Prince Regent battle,  so yes Princess Yong'an is not working with VM Lai. (apparently, because who knows...Yan 3rd lady was poisonned with moth venom leaving her palace o_O)

Who is her daughter's father? I don't know.

=> Shen Du has to prove the 3 remaining accusations and his father's name will be cleared.

I love this show and I am happy that you enjoy it aswell
Hope it helped.

The royal family and court is like a precariously balanced house of cards and Yan Xing is the recklessly thrown baseball that sends everything flying. 

They just added a new character to the roster: the late Emperor's concubine. Maybe she is Lai Luozhi's mother. He was strangely unperturbed by his sister's death (Chen Houe) and watching his other sister agonising in pain after King Xian's banquet. He could be a direct heir to the throne!?

 DefyingDestiny:

The royal family and court is like a precariously balanced house of cards and Yan Xing is the recklessly thrown baseball that sends everything flying. 

They just added a new character to the roster: the late Emperor's concubine. Maybe she is Lai Luozhi's mother. He was strangely unperturbed by his sister's death (Chen Houe) and watching his other sister agonising in pain after King Xian's banquet. He could be a direct heir to the throne!?

You maybe right. The family history of VM  Lai Luo Shi is very mysterious. 

His relationship with his mother especially. We had a glimpse of it when he approached Lu Chui Chui. This is very fishy. If ever VM Lai becomes a direct heir to the throne. His conspiracy would make sense and he would be deceiving everybody (The Dowager, Prince Xian and Princess Yong'an in particular). That would be massive plot twist. 

The royal family is like a snake pit. Everyone is fighting for survival. You could even name it kingdom of collusion. (house of cards is a good metaphor too)

Well ... They gave us a great drama. The main antagonist was well hidden until the very end. They got me/us on that. Who would have believed it o_O