Takeru’s attack may have looked like a full-on assault, but Koku is able to kill the young child pretty quickly.
Less than 24 hours later, Keith has turned himself in and is sitting in an interrogation room with Eric. His handcuffed wrists sit on his lap, indicating he is in no distress and is putting up no resistance.
Keith’s theory is that whoever is heading up Market Maker is the person responsible for killing his sister Erika, and that that same person is the one who has been killing the Reggies. Eric confirms that Keith has a suspect in him about who this top dog could be, but Keith says he can’t make his move yet because he doesn’t have irrefutable proof that the suspect is who Keith thinks he is.
With time running out, Eric asks Keith how he’s going to confirm his suspicions and Keith starts to whine that Lily is the reason why he hasn’t made more 
progress. This comment flips a switch in Eric and he starts freaking out at Keith that about how he knew Keith couldn’t do anything by himself, so he gave Keith a team of people to use at his disposal.
This is the signal. Lily, Boris and the others immediately enter the interrogation room and set up a command centre. Eric explains that after Erika’s fake trial eight years ago, after he had to arrest Keith for what happened as a result of Keith acting alone, he learned that they had needed a team to do what they needed to do; now Keith has his team. For the next 6 hours, until the Royal Investigative Service is forced to turn Keith over to the authorities (after which the RIS will be disbanded), Eric and the others will obey every order Keith gives them. Wow! 😀
Keith reveals that he had bugged Gilbert his first day back at work, so now we know Gilbert is who Keith suspects of having killed Erika.
Keith’s first big plan is to change Lily’s appearance slightly to better resemble Erika, then send her into Gilbert’s office in the pretense of getting a book signed. The goal is to trigger Gilbert into making some kind of move I’m assuming.
Later up on the Moby Dick, Takeru’s twin Kukuri confronts Minatsuki over Takeru’s death. Without barely flinching Mintsuki cruelly strangles Kukuri and throws her aside after she taunts Minatsuki with her knowledge of his plans.
Keith’s main plan is to use Lily as bait for Gilbert. Now that their first plan has focused Gilbert’s attention on Lily, the team bugs her and has her wait at a bus stop to see if Gilbert will offer her a ride home. Of course he does; Lily still resembles Erika after all. While Lily rides in the car with Gilbert, Boris and Mario are following the pair in another car using GPS.
Gilbert’s expression in this scene is… honestly a little creepy. Very flat with no life in his dead eyes.
Lily continues to maintain her act of being Erika, but she screws up when she turns on the radio and sets it to a techno-ish station – music Erika wouldn’t have listened to. Gilbert would know this because he knew the real Erika. Keith picks up on this realization and is alarmed, but for some unknown reason he doesn’t mention this to Eric. Maybe he hopes Lily will be able to recover the situation. However it’s too late – Gilbert now knows something is up, and Keith’s plan goes sideways.
Gilbert pulls his car into a car wash and Boris and Mario follow. From the outside, everything looks normal. When the wash finishes, Gilbert’s car resumes its new path. He’s no longer heading towards Lily’s place, so where could Gilbert be going?
To his house, apparently. Boris and Mario sneak up the driveway towards Gilbert’s parked car and confirm no one is inside. Is Lily inside?
The house looks abandoned. No lights are on and the wallpaper is peeling. Everything is dirty and rotting. How could Gilbert live here? Boris and Mario pull out their guns while they search for Lily. Suddenly the hear noises from the floor above them, so up they go to continue their search.
When they burst into a closed room they see a white-haired man holding a figure in a blue coat. But this isn’t Gilbert and Lily – it’s two Reggies, with one resembling Gilbert. Taped to the coat of the fake!Gilbert is Lily’s bug and microphone. She’s gone!
Fake!Gilbert opens his jacket to reveal a bomb, and Mario and Boris immediately attempt to flee the house. The bomb explodes before they can get out though and the RIS agents’ signals cut out. Thankfully both men are still alive.
Keith figures out Gilbert’s grand scheme: for the past 8 years, whenever Gilbert has committed a crime, he has traded places with a lookalike Reggie he had waiting, likely rewarding him with that gold liquid as an incentive. Gilbert still gets his victim but gets none of the blame and if the Reggie becomes unstable then he is released into society with no ties back to Gilbert. Seems like a pretty perfect plan no?
Eric panics and tries to put out an all-points-bulletin for Lily, but Keith insists that they carry on with their original plan. Changing the plan now would reveal to Gilbert that they know about the switch and that Lily is missing. Keith points out that emergencies pop-up all the time in police investigations and overreacting to them is why he and Eric failed the first time they tried to investigate Erika’s death. Keiths pleads with Eric to trust him and Eric backs down.
At the very end of the episode, Lily wakes up in what looks like some kind of hospital or laboratory. She’s face-down on a steel table and there’s a cart with metal surgical instruments next to her. Looking around she can see people floating in glowing blue tanks.
Gilbert approaches Lily and starts talking to Erika, almost ignoring Lily completely aside from touching her. He theorizes that even if Keith catches onto his place, by the time he finds Gilbert’s hiding place Lily will be dead and mutilated. Only time will tell.
I’ve seen this anime before so there are no surprises for me anymore in re-watching this for the readers request, but I remember how confused by Gilbert’s switch I originally was. I think it is a well-executed twist that really throws viewers for a twist as they try to figure things out.