Kate, Jack, and Locke make progress in the tunnels connected to the hatch.
On the day Michael set out for his round-the-island excursion with Jin, Sun, Sayid, and Shannon, Kate approached Jack with her suggestion that they use the dynamite to blow up the metal door in the tunnel connected to the hatch. Jack thought before answering. He, too, was anxious to find out what was down there. But someone would have to transport more sticks of dynamite to the hatch, and then descend the ladder with them, or lower them down on a rope, and then carry them to the door. Kate would insist on doing it herself, or at the least draw straws for the honor. Even if she swore she would be extremely careful this time, Jack felt it was too likely she would blow herself up and ruin everything.
Eventually Jack answered, "I'm afraid that I have to agree with Locke on this one. We shouldn't press our luck with that stuff yet. If nothing comes of clearing the rocks we can always resort to dynamiting the door as a last resort, but if something goes wrong with that, we'll never find out was is down there. And remember, no one is forcing you to do this."
Kate had enough experience to recognize when someone wasn't being completely truthful, but an open accusation at this point wouldn't do her any good. The two-against-one scenario she had hoped for with Locke being the one had not panned out; instead she was the one against the other two. There was still too much distrust of her among most of the castaways for her to make big decisions opposed to what the more trusted doctor thought. Nevertheless, she would eventually prove herself no matter what.
Before leaving, Jack checked on his patients. Sawyer was resting as comfortably as could be expected in the circumstances, and gave a definite impression that he did not want further attention. Claire had been doing better with Aaron now that the threat to her baby was over. She sympathized with Michael over his loss, but she had to be there for her own child. Charlie was physically okay, but frequently looked agitated. He had thought the threat to Aaron was over, but the news about Walt left him doubting. Besides, that crazy French lady was still on the loose, and there was no telling what she might do.
Satisfied that he had done all that was practical medically, Jack left with Kate, Locke, and Hurley for the beach to gather materials from the plane wreckage that would help them clear away the rocky debris in the tunnel. In particular they were looking for long, thin pieces of metal that could be used as levers. While they found several of these, it took a lot of effort to detach them from other parts of the plane. With much prying and hammering, they finally managed to get eight pieces of metal ranging from two to four meters in length, and a few centimeters thick. However, this took most of the day, and they could only make it back to the caves.
The next day, the quartet went back to the hatch. Kate wanted to simply drop the levers down the opening, but Locke insisted that they be lowered down by rope so that they wouldn't be damaged. Again, Kate relented, and Hurley did the honors of lowering the levers while the other three climbed down the rope ladder. The three came up with the idea that one would stay at the bottom of the ladder while the other two worked at clearing the rocks. Three people would have been getting in the way of each other, so that arrangement worked rather well. Furthermore, each would be getting a break one-third of the time.
Still the task seemed interminable. Over three days literally tons of rocks were pushed aside, lining the corridor, with no apparent end in sight. On the morning of the fourth day, Jack was at the bottom of the ladder when he heard the signal of five whistles from Hurley.
"What is it, Hurley?"
"Real bad storm coming fast, dude. Better get up here right away."
Jack remembered the warning from Arzt about the approaching of monsoon season. He couldn't afford to be stranded away from the patients at the caves that might need him. Locke and Kate were much less eager to leave, but Jack was insistent and they went along. They were pretty drenched when they made it back to the caves, but were none the worse for wear. The storm lasted just about one day, and they returned the next morning. Nothing interesting happened that day, but on the next, they finally broke through to something. They managed to clear out a hole that was only large enough for Kate to crawl through. Impatient, Kate got Jack to retrieve Locke, who was waiting his turn at the bottom of the rope ladder, and then the two men forced their levers through the hole to prevent any possibility of it collapsing on Kate as she crawled through.
Carrying a flashlight, Kate found herself in a continuation of the tunnel. There were more featureless cross tunnels terminating in dead ends, but at the end of the main tunnel was an arch with some indecipherable figures drawn on it. Kate proceeded through the arch, but her way was blocked by more heavy rocks. "Not more rocks!" she thought, but this disappointment was overwhelmed by the discovery of the extended tunnel network. Excited that she had discovered something interesting, she returned through the hole where Jack and Locke were waiting.
The three returned triumphantly with Hurley, but as they got to the caves shortly before nightfall their enthusiasm was tempered as they were greeted with some unfortunate news. Sun and Jin, along with a very distraught Michael, had just helped the wounded Sayid and Shannon back to the caves. The injuries were moderate, but would not be life threatening with prompt medical care. Sun had done a good job of patching them up with the gear they had on the trip. Jack redressed the wounds, administered some antibiotics, and ordered them to rest for at least a day.