You begin at a farm; go into the house #1. You will find yourself in a kitchen. There's a broken tap right by the sink - attach it using (WL) #2. The pans blocking the passage will fly into the sink.
There's a painting above the chimney - you can wave to it #1, but you need a ginger girl. Search the door - use (WL) on the sofa on the left, shoot the purple chair and use (WL) on the blue chair. Eventually you will find the hidden girl #2.
Now wave by the painting and throw the pot (WL) into the chimney #1. Hagrid will join you. Use the broom on the mirror #2 to clear it off of dust.
In the reflection, you will see a chain now visible in reality. Switch to Hagrid, approach the designed spot and pull the chain #1 - a few bricks will fall out of the hand. On the left you will find a big chest, which attacks you as only you approach it. Shoot it from a distance #2. You will get a couple more bricks.
Use all the bricks to create (WL) a sword, which you should then send (WL) to the wizard running from the dragon on the painting #1. He will throw you a key - use it to open the padlock on the door on the right #2.
Once on the alley, shoot the colourful boxes - chain pieces will fall out of the red one. Attach them to the wall (WL) #1 and then use Hagrid to pull them #2. The road will be unlocked.
A bit further a big spider will attack you - treat him with magic twice #1. At the end of the alley you will another chain - use Hagrid to pull it once more #2.
You will begin at the Grassy Courtyard (M3.34). In order to open the gate, you have to first create a Strengthening Potion, which will allow you to pull the chain. The snake's fang can be found in the flowers #1, use magic two twice (once on the flowers and then on the snake). On the right, in the flowers, you will find a piece of a skeleton. Use magic on every bush and then put it back together (WL) #2. You will receive another ingredient - the skeleton hand.
On the left there's a cleaning machine #1, use magic on it. Once it finishes cleaning, it will spit out the last ingredient. Drink the strengthening potion and pull the chain #2. Leave the courtyard.
Follow Nearly Headless Nick to the Herbology Class (M3.30). You will learn how to act with Mandrakes. Approach the shelf at the end of the room and use it - you will put on the earmuffs #1. Now grab one of the three Mandrakes and put it into the pot #2. Do the same with the other two.
Leave the class and head to the Fountain Courtyard (M3.28). There's a Mandrake blocking the path. In the left part of the courtyard you will find a wardrobe #1 - put on the earmuffs. Pick up the flower and put it into the pot #2.
Follow the ghost to the Lessons Hallway (M4.35). On the left, right next to the entrance to the Transfiguration Classroom, you will find a wardrobe #1. Put on the earmuffs and pick up the Mandrake shouting by the glass passage to the Defense Against the Dark Arts Classroom. Break the passage #2, put the Mandrake into the pot and go into the classroom\.
You will be acquainted with the Immobilus spell (IM). There are three Cornish pixies flying round the classroom #1. Use (IM) twice on each of them - first to and then to finish each off. After a short cutscene, five more pixies will appear - eliminate them in the same way, by using (IM) twice on each of them #2. Leave the classroom and head to Quidditch Grounds (M3.26).
Open the hatch #1 and jump down. After a while a ball will appear - in the chest you will find a bat, which will hit it into the blockade on the left, once you use magic on it #2.
Assemble a trampoline from the scattered bricks (WL), jump off of it and jump higher up. Use magic on Dobby #1. Switch to Hagrid, pull the chain and move on #2. Attack Dobby a second time.
Use (IM) on the two pixies holding the door #1 and afterwards (LS) on the Devil's Snare. After a while the snitch will fly out and a part of the stand will crumble. Create a staircase from the scattered bricks #2. Dobby will manage to escape.
Go up the ladder onto the second platform. Use (WL) to lift up the big purple brick #1 and attach it to the chain - the gate will open. Go up the left ladder and attack Dobby #2. Use Hagrid to pull the chain - you will free the dragon and two bricks from the cage.
Set the bricks so that you can get upstairs #1. Dobby has hidden inside the middle wardrobe #2 - chase him out and attack.
Jump down and eliminate two pixies holding the bridge using (IM) #1. Afterwards use (WL) on the barrel, to throw Dobby out and attack it for the last time #2.
You have to prepare medicine for Harry. You will take control of Madam Pomfrey, who knows all the spells. The first ingredient can be found behind the glass showcase - you have to use a Mandrake to break it. You can just pick it up using Madam Pomfrey #1, or wear earmuffs with any student - first you have to destroy the padlock in the wardrobe #2. Do it using Madam Pomfrey, casting Reducto.
By the bed of one of the patients on the right, you will find a skull. Connect it with the body using (WL) #1 and eventually the student will destroy the skeleton - you will get the second ingredient. Pick up the bed on the left (WL) and afterwards assemble the armour below the bed (WL) #2. The armour will destroy the big padlock, opening the passage to the next room.
Right after entering the second room, you will find a purple spider web on the wall. Use the broom (WL) to sweep up the webs #1. After a while a spider will shot up. Knock him down using magic and bring the ingredients to the cauldron #2.
Follow the ghost to the Great Hall (M1.3). You will learn the Expelliarmus spell (EX). You need to destroy five dummies appearing from behind one of the three doors with both Harry and Ron #1. A duel will begin; try to hit the enemy five times using (EX) #2. You also have to look out for his spells - dodge them. Be aware that he will also try to dodge your attacks.
You will also learn to speak Parseltongue. Follow the ghost to the House Hallway (M2.11), to the Slytherin Dormitory entrance to be precise. Talk with the snake #1 and he will throw out three bricks. Place them on the platform on the left in the right order #2, beginning with the tail and ending on the head.
Go into the Slytherin Dungeon (M2.12). Approach the entrance #1 which won't let you in. Leave the dungeon and head after the ghost to the Potions Classroom (M4.42). You will learn how to prepare the Polyjuice Potion. Approach the bricked up wall on the left and use (WL). Inside you will find a pixie holding an apple #2. Get rid of it with (IM) and throw the apple into the cauldron.
Pick up the chest using (WL) #1 and a snake will creep from the basket, kidnapping one of the students - he will leave behind some hair, another ingredient of the potion. On the table on the right you will find a pot and three bottles - use magic on them to pour their content into the pot. After a while a flower will grow out #2 - take the cherry and throw it into the cauldron.
Drink the potion - now you can freely choose a character into which you want to change #1. Just be sure to choose a Hufflepuff house member. If you haven't unlocked/bought any yet, use the newly gained Justin Flinch-Fletchley. Wave to the painting #2
Leave the classroom and head to the Main Hall (M1.1). Use the Polyjuice Potion once more. Use magic on the yellow and blue flag by the stairs - you will find some hair and an apple #1. To get the cherry, use the (WL) on the blue mechanism #2. Once more choose a character representing the Hufflepuff House, for example Justin Flinch-Fletchley.
Use the broom twice (WL) #1, first cleaning the trophies and then the painting. Wave to the painting. Go up the stairs to the Bathroom Hallway (M1.4). Head after the ghost right, block the pipe using (WL) #2 on the pieces standing on the shelf. Move on and after a short cutscene; go through the door to the bathroom.