Previous Episode
This is perhaps the BEST Bungou Stray Dogs season by far. Everything is just PERFECT!!! Rampo and Fukuzawa getting more screen time, backstories, and ofc animation.
The previous episode was a bit confusing as it was more about a murder mystery. It seemed like Rampo wouldn’t be able to solve this case, however, he proved all of us wrong in the end. A mysterious character named Nikolai also made an appearance in the end. I’m excited to see more of him.
Award Ceremony

The episode started with Fukuzawa receiving an award from the Government in recognition of the Armed Detective Agency’s services. Some people had their doubts regarding the Agency, however, the Assistant Senior Attorney shut their mouths. He seems like a NICE guy!!
A New Case

Kunikida was finally released from Prison and was training Atsushi as he believes that his fighting skills are not up to the mark and he is depending way too much on his special ability. Following this, the Armed Detective Agency had a meeting regarding a special case. It was about mysterious murders. The victims of the murders were tortured and it looked like it is a secret message.

Rampo concluded that it is the message of the Decay of Angels. It consists of 5 murders, however, in this case, there are just 4. Meaning that one murder is still left. Fukuzawa announced that they’d try their very best to stop this murder. Rampo suggested that they should not accept this case as Mushitaro warned him about him. In the end, it was decided that the Armed Detective Agency would solve this case without Rampo.
Armed Detective Agency

After this, As Atsushi was looking through the files, he received a call from Ango who was looking for Dazai. He told Atsushi that a Government Department is behind all of these murders. Meanwhile, the Assistant Senior Attorney we saw, in the beginning, met Atsushi. He lied that he was drinking coffee and Atsushi immediately realized this. He made an excuse and ran away.

After Atsushi ran away, the Attorney concluded that the Armed Detective Agency is already DOOMED!! Dazei, on the other hand, was witnessing a horse race when he met a blind police officer who arrested him because the police had suddenly received evidence regarding his old crimes.
Department of Justice

The Attorney and the Department of Justice were behind all of this. He wanted revenge against Fukuzawa because he had murdered his father in the past. They had collected evidence against all members of the Armed Detective Agency. Now, this is where the fun begins.
His assistant who had collected all the evidence turns out to be NIKOLAIII!!! He shot him in the leg and took all of the member’s hostages. He also recorded a message for the Armed Detective Agency in which he threatened to kill all of them if they do not come to save them in time.
Mysterious Book

Meanwhile, Rampo was looking for evidence regarding the DOOM of the Agency. As he was looking, he found Chief Taneda who was shot and left to die. He told Rampo about a mysterious NOVEL with the power to make anything come true. However, the writing should have the casual consistency of a novel which makes it hard to use. With this, Chief Taneda fainted.
Nikolai vs Atsushi

Atsushi was sent in first because he is the fastest one out of them. After reaching their hideout, he decided to take the basement. However, his decision was not that WISE as he encountered on the way.

Nikolai possesses the special ability of Matter Teleportation. He can teleport anything within 30 meters using his ability. It seemed like Atsushi had the upper hand as he destroyed his gun. However, Nikolai was thinking way ahead of him. He teleported a tree out of nowhere and slammed Atsushi into the wall. With this, Atsushi’s chances of winning died. Nikolai tortured him a bit and revealed his silly reason of doing all this. After this, he captured Atsushi and teleported away.
Trap

Armed Detective Agency and the Military Police also arrived on the scene. Kunikida sent one of the members to take care of the Military police as they did not want them to interfere. After this, they went in and devised a plan to capture the perpetrator. However, little did they know that all of this was a TRAP!!!!!!! Nikolai activated the Chainsaw that would kill the members; somehow, Armed Detective Agency members were the ones behind all of this. Nikolai was also one of those who had died.
The Attorney was forced to make a phone call to the Military police revealing that Armed Detective Agency is behind all this. With this, the episode ended.
My Opinion
I’m still not sure HOW and WHAT happened in the end. Well! We know Nikolai’s ability. It was not his doing. Someone else is behind all this and I suppose they will be revealed in the next couple of episodes.
Now, the main thing here is, HOW will the Armed Detective Agency get out of this mess? Mushitaro was right when he said that this case will DESTROY them.