You start at the Docks behind the Cherry Tree Hill Police Station. Ellie will explain that you now be able to take a train to Bluebell National Park. You have to go there to find Clarence "Stinky" Fletcher which might be the old guy in the cutscene, once you get into the mining chambers.
Whistle whistle[edit]
So go to the nearest train station and accept the ride. When you reach the outside mine area, notice you can't go in yet. So in order for the mine workers to take a break, go to a shack with the robber crowbar sign. Attach and sound the horn so they can leave the area. Go in for your next assignment.
Train stations are rarely important when you don't have cars to use. Along the rails, there are empty brick areas where you can build more train stations so look through the map and drive over there to confirm it. Last of all, don't bother driving on it, otherwise it will take forever.
Special Assignment 3: Miner Altercation[edit]
Consider how big the mine area is, you'll need your wits to get through the assignment. So make your way to the top to the cabin where you find your mine outfit.
Mine outfit is important for breaking grey boulders that you can't normally do with an average Lego person. So look out for places where it could hide icons or super bricks. The other important use is handling dynamites. Conveniently, you'll find it in like a soda can machine. If you're working in any assignment, you'll only have one use per area. Use it again and the machine explodes. But when you use dynamites outside, you can use it as many times as you want.
The next area has one new feature that will tests your limits as a skydiving and I'm not talking just jumping out of aeroplanes!
Skydiving can take practice and timing. 
to speed up and 
to slow down. You'll encounter studs in a circle and if you go through it, you'll take it all! Make sure to really avoid obstacles or you might start over in the middle of it as it can take quite a lot of getting use to. Keep a sharp eye as you go down the epic size of a mining cave!
Assuming you get through all the trouble, you can get the recording of what happened to "Stinky".
Cutscene summary. You meet Rex Fury but you'll end up seeing stars instead after he punched you. Then gets away in an ice-cream truck! You wake up seeing Natalia finding her dad and Huckleberry giving you a card to see Barry Smith at his dojo via Chinese Temple.
So you need to learn kung-fu in the midst of your detective quest. Continue left outside until you see a Chinese arch on both ends (The bridge further on the road is under construction and won't open until you finish the requirement). Make sure you have 30,000 bricks to make the bridge. Then after you cross it, fork right up the stairs for your next assignment.
Special Assignment 4: Kung Fool[edit]
This is pretty straight forward. You won't find like a karate costume here but your combat skills will be enhanced after finishing this assignment. Anyway, the goal is to get the key from an ice statue that the man is making. How? To make a dragon with 40,000 bricks!
Observe the area as there are a few things to do. On the left of the entrance, there's the sliding puzzle which should be easy in order to get the flag. On the right of the entrance, you have a tablet that takes you to another flag. This lets you get the dynamite after a crash into the gong!
Get to the roof as there's two more flags to get. Knock the Chinese dragon ladders down and a lantern in which you need a grapple (police uniform) to reach the top. Light both sides and bring the remaining flags. Doing those actions allows the super bricks to appear as 10,000 bricks each. Build the dragon to scare the ice sculpture guy in order to get the key.
Inside the dojo, find a hammer at the end of the hall and hit the gong on the left of that object. Then you go through this exercises to give your combat more flexibility since your opponents will get tougher.
Cutscene summaries: Barry gives chase a CD to listen to but it makes a funny sound causing him to collapse. This scene gives homage to "The Matrix", well replacing serious kung-fu with a humorous twist like tickling and smacking Chases' butt! The second half: Barry Smith took his belt off and see his underwear in full view, Lego style.
Advance moves really gives you a slight edge against tougher enemies. Your blocks now is replaced with counter attacks instead. Also certain tough dudes requires you to rapidly tap the grapple button and throw that bad guy. These are more useful but still, as a police officer, you're job is to cuff them at the end. Not in the dojo but out into the city.
Crashing the party![edit]
You get a call from Frank Honey and he's stuck in Crabby Cove in Fort Meadow. Well find the stone bridges leading to a beach area. What's worse he's stuck inside a long truck! Anyway, take care of a dozen or so thugs before driving this behemoth! There will be continued chase from those thugs so watch those eight hearts. One solution is to drive through the bridge and underneath to shrug off the thugs as you reach back to the police station just outside the bank area.
Cutscene summary: Well, Frank crashed the party with his truck just to impress Ellie? Oh dear. Chase comes in the scene and Frank told the mayor that he stays out of Dunby's case! Chief Dunby feeling embarrassed goes along when Chase mentions the Chan Chuang Gang allowing you to go undercover for the first time. You get the costume from Ellie to make you look like one of the bad guys? Well at least it works as he goes into dangerous territory.