This part will take you through the mission to save Midna.
Once Link leaves the Lakebed Temple, he will reappear at Lanayru Spring, where he will meet the mysterious evil person that Midna was talking about -- Zant. Lanayru will emerge from the spring to deal with this intruder, but Zant will knock him back with a shock wave attack, causing him to disappear. Link will also be knocked to the ground and changed back into a wolf as Twilight again covers the spring. Zant will hold Midna spread-eagled in mid-air as he takes the Fused Shadows from her, calling her a foolish traitor for trying to take such a power to use it against him. He will then say that the power he wields is not that of her people, but that which comes from "his god". Zant will bury something into Link's forehead before he pulls Midna to him, saying that he needs her power so that the world of light-dwellers will also become their world. Midna refuses to give Zant what he wants, so Zant decides to cast her into the light world, causing her great pain and making her body colors reversed. However, Lanayru transports Midna and Link out of the spring and onto the part of Hyrule Field north of the Castle Town, where Link wakes up to find himself as a wolf again and Midna near dying. He is then told to go to Princess Zelda, for she holds the key to freeing him from his wolf form.
Hyrule Castle Town
From where you are, proceed on the road to the east entrance of Hyrule Castle Town and enter, heading for Telma's Bar. She told Link earlier that there's a passageway from there that leads to the castle. When you try to enter the bar, however, you will be kicked out by its owner. Head back to the outside court area and you'll run into Telma's cat Louise (as in like the girl buddy movie), who will tell Link that she knows a way we can get to the passageway. There's an entryway on top of some big boxes we need to climb up to, so push another big box up to those boxes and then you'll be able to reach it. Inside, we need to carefully walk across the ropes and the ledges without causing any of the jars up there to break, and also without falling, which will attract the attention of the people in the bar. You can let out a sigh of relief when you reach the door.
In the next room, there is a lantern floating around in mid-air in front of a golden person sitting in a chair, scared stiff with a cat stuck on his head. Drop down into the room and go into sense mode to discover that it is a Poe who's haunting him. Attack the Poe to knock him down, then tear at him to finish him off. This will release a Poe Soul, which you can collect. The man will introduce himself as Jovani, who was so consumed by greed that he sold his soul to a dark creature that immobilized him. To free him of this curse, we need to collect 20 Poe Souls, for which he will reward us with a bottle of Great Fairy's Tears; if we collect 60 of them, he can get rid of that golden complexion. He will open up a treasure chest that will allow us to drop down into the underground walkway.
You'll slide down a water chute into a fountain-like room where there are some rats that will harass you. Quickly get rid of them and pull on the chain that will open a gate to another water chute that will take you down to a door at the top of some stairs that has a spiderweb over it. Take down the two Skulltulas that will appear in front of the door, then pick up a stick and light it on fire with a torch so you can burn away the spiderweb and go through the door into the next room. Here there are four torches that can be lit, but our main thing is to burn away another spiderweb on top of some stone blocks on the west side of the room; the torches are simply there so you can have another source of relighting the stick. Past that spiderweb, slay the Keese and the Bokoblins and head for the door that will lead you to a spot where you'll have to dig to get to another path.
Go north and then to the left from where you emerge, and you'll be back at the winding staircase that you went up earlier when the castle was in Twilight. Here you won't have the benefit of Midna helping you out with Midna-jumps to make it across gaps, but you will have lots of ropes to walk across in order to get to higher portions of the stairs. Here be careful of the Bokoblins along the stairs when you attack them, because you might end up falling down to the bottom of the stairs, requiring you to go back up them again. When you reach the top of the stairs, go through the door to exit the tower.
We're now back along the rooftops again to reach the tower where Princess Zelda's chamber is. Slay the Bokoblins along the first walkway, then get on the wooden platforms to the left and jump down to the next walkway, watching out for the Kargarocs. At the end of it, wait for a sheet of canvas to be level with you so you can quickly walk across to the top of a tower from where you can drop down to the roof on your right. Make your way to the window that you climbed in earlier and then go up the stairs after entering.
When Link enters Zelda's chamber, she notices Midna's condition and what has happened to Link despite his efforts. Midna will tell Zelda she needs to help Link, because she needs him to save her world. Zelda tries to use her power to restore Link to his Hylian form, but then says what binds him to his wolf him is a different magic than that which transformed him when he entered the Twilight, so in order for Link to reclaim his original form he must head for the sacred grove in Faron Woods where he will find "the blade of evil's bane" -- the Master Sword. Midna will ask as her last request for Zelda to tell Link where the Mirror of Twilight is located. Instead of doing that, however, Zelda uses her power to restore Midna's life, sacrificing her own life in the process. Midna realizes the cost of that sacrifice and decides to make it count for something as she now accompanies Link to Faron Woods.
NEXT: Getting the Master Sword