As Samus takes the lift down, a cutscene will play depicting the Mother Brain watching Samus closely with an "eye of Sauron" flair. Once the game returns you'll find yourself in Norfair, complete with a remake of the original Norfair's tune playing. Before locating the Ice Beam, we'll need to go and find the Power Grip (you don't have to for sequence breaking) to enable Samus' ability to hang and climb up the edges of platforms.
Descend the elevator shaft down past the purple Ripper and save your game in the room on the right before carrying on. Head left once you're ready and cross the long fiery corridor beyond the elevator shaft. Along the way you'll spot Missile NO.01 but we'll pick it up on the way back once you've found the Power Grip. Beyond this corridor you'll find yourself in another shaft with an elevator not far up.
Hitch a ride on it to find yourself in Crateria - there's a few items you'll want to pick up here.
Head right in this dank cave and blow through the wall blocking your path. Go through the door you'll find to discover a massive water cavern filled with Skultera swimming about. From here you can pick up Missile CR.01 underwater even without the Gravity Suit. With the Missile tucked away jump up to the top-left corner of the cavern via the floating platforms.
Blow down the obstructing wall and climb up through the opening in the ceiling not far ahead. You're now in an outdoor area conveniently named the Chozo Ruins. Activate the Morph Ball and roll through the narrows tunnels on the right to eventually reach an enclosed door not too far away. Go inside to find another dank cave, where you'll locate Unknown Item #1 in the corner (doesn't that mysterious item jingle tune make you shiver? heh).
The game will tell you that this weird item isn't compatible with your current suit, but sooner or later it will be (you should be able to tell what it is by the item's appearance). With the Unknown Item in your possession you'll be able to destroy the large blocks scattered about in this area, so give it a try and pick up Missile CR.02 while you're at it. Head back outside and make your way up out of the ground to the open air.
There's not much to be found over on the right for now so head left and jump up the platforms to reach a door within the beaked maw of a large statue. Go inside to find another desolate area decorated by giant intimidating and crumbling Chozo Statues. You can't walk over the bridge spanning the gap ahead without falling through, so face the inevitable and drop down to find yourself at the base of a tall shaft.
Break through the wall on the left corner and navigate a short series of tunnels to find a hidden room beyond containing the much-needed Power Grip upgrade. Use it to escape from this room, and as you re-enter the shaft the large statue in the center of the room will begin to rise.
Once it reaches its peak small platforms materialise for you to climb back up. Aren't the Chozo champs? Ascend the shaft and head left at the top. Cross through the next empty room to find the massive landing site where Samus' ship resides.
Save your progress in Samus' ship then proceed through the right door in the corner. Cross this following corridor to find yourself back at the Norfair elevator. Ride it down; we'll now go and track down the Ice Beam. Before going back to the room housing the elevator leading back to Brinstar you should pick up Missiles NO.01 & NO.02. Back in the Brinstar elevator shaft, head right and save your game before moving on.
Proceed right to locate a giant lava cavern filled with a variety of platforms and enemies. Make your way to the right side of the cavern, making sure to stay away from the bomb launchers in the ground. Once at the right side go through the door to find yourself in a shaft apparently leading skyward. What you don't know yet is that this place is the tallest shaft in Norfair, and you'll be coming back here numerous times.
For now ascend the green shaft and head through the first door you'll find on the left. Use the small blocks suspended above the lava in the following corridor to make it through safely, then head left once more to finally find the Ice Beam. With your latest Beam upgrade in hand, you'll have to head left as the green door sealed behind you can't be opened without Super Missiles.
Bomb through the wall behind the Chozo Statue and move on, freezing the purple Ripper to reach the door. In the following shaft you'll find a Save Room on the left, once you're ready climb up the shaft by freezing the Ripper flying about. Use them as stepping-stones to reach the apex of the shaft before heading right. In the following corridor use the enemies jumping out of the lava as frozen steps to proceed through, eventually you'll find a Chozo Statue with outstretched hands.
Jump on and the map will show you where to go next - right into Kraid's lair. The glowing dot will center on the room right behind Kraid's, so you know what's coming. For now go right again and pick up Missile NO.04 before leaving. Re-enter the tall shaft you were in earlier and backtrack to the Brinstar elevator, picking up Missile NO.03 on the way.