The Second Bombing Mission

Head to the train station and board the train. After Barret's dialogue, Tifa will speak with you.

The train's security alarm will sound, locking cars sequentially. This section is timed. Run through the cars to avoid having to walk further.

In the second car, speak to a man near the transition to receive a Hi-Potion by choosing the top dialogue option (“Yeah…”).

In the third car, a punk will steal 100 Gil. Tell him he's busted to get it back. His girlfriend at the end of the train may steal it again; try to catch her in the next train car to recover it.

In the last train car, proceed to the end and talk to Tifa. After more dialogue, you will jump off the train.

You will find yourself in a “Winding Tunnel”. The better you performed on the train, the closer you are to Reactor 5. Heading north leads towards the reactor outskirts. Heading south leads to clone tunnels with Shinra guards, a potential grinding spot.

Continue north until you reach the northern-most tunnel with security lasers. Approach the air duct on the floor and enter it after the dialogue.

Inside the first duct, head north-east and pick up an Ether, then climb down a ladder.

Climb down another ladder to a maintenance area. Head to the south-western most ladder to find Wedge.

Climb the ladder near Wedge to find Jessie in the ducts. Collect a Potion south-west of her.

Find another ladder down a tunnel to the south-west.

Descend another ladder and follow a walkway to find Biggs. Continue north-east along another walkway to find a Save Point and a Tent. Use the Tent to recover HP/MP if needed.

Climb the ladder and go down a tunnel to reach No. 5 Reactor.

Slide down a pipe to the reactor floor. Head north-west to a doorway. Follow the path: go through the doorway, leap a gap, climb down a ladder, walk down a ramp, descend another ladder, cross pipes, and go down another ladder to reach the bottom of the reactor.

Find a Save Point at the bottom. The enemies here are slightly stronger but not particularly noteworthy.

Head south-east from the Save Point to reach the reactor core. Cloud will have a flashback.

After dialogue with Barret and Tifa, Cloud will recover. Set the bomb.

Backtrack to the first area of the reactor and head up the stairs opposite the doorway you entered.

Enter and ride an elevator up. In the rooms above, loot a chest in the first room for an Ether.

Head north-west into another room with three terminals. The party will split up to activate them.