I first caught sight of Karim Sar in 2007 from the top of a small, previously unclimbed peak between the Baltar and Toltar glaciers. Lorenzo Corona identified the lovely ice-capped mountain to the south as the one his friend Ivo Ferrari was attempting that year with two mates; Lorenzo even had the expedition postcard! I took photos and stored the peak away in the back of my brain.

Two years later, I had planned to attempt the south face of Kampire Dior, but in May the Taliban invaded the Swat Valley and our expedition outfitter became reluctant to take us close to the Afghanistan-Pakistan border. Two team members pulled out. Time to change plans. I remembered Karim Sar and learned that it was still unclimbed.

On June 5 Paul Hersey and I arrived in Islamabad to discover security at an all-time high. We drove north up the Karakoram Highway against an endless tide of refugees fleeing the Swat Valley. Three days after reaching the relative safety of Gilgit, we were ensconced at base camp beside the Shilinbar Glacier, under the south face of Karim Sar. The face was a confusing mass of steep snow slopes, hanging glaciers, and granite rock bands, culminating in the summit ice cap. With a vertical relief of 2,600m, it was a daunting sight.

As we acclimatized over the next week, Paul struggled with the altitude in snowy, unsettled weather. Summer was late to arrive, and there was vastly more snow than during the previous two years; we learned later the Karakoram hadn’t seen as much winter snow in 30 years. At base camp Paul came down with an undiagnosed illness, recovered, and then decided he didn’t want to go onto the mountain. I felt a mix of despair, anger, and anxiety; the expedition was heavily sponsored, and, for me, giving up without an attempt wasn’t an option. I decided to try the mountain alone and succumbed to some angst-ridden, sleepless nights.

The morning of my departure for the summit, Paul announced he would come back up the glacier to advanced base camp (4,200m). I felt a flood of gratitude—even if Paul were thousands of feet below me, it would be a huge relief to know he was there. Moving up through a dangerous section of the icefall, Paul climbed with new speed and confidence. The next morning he agreed to come a few hundred meters up the face to belay me through a rock band. When we got beneath the short granite pitch, I realized that ice cliffs 1,500m above ringed the terrain. I decided to follow a gully system to the left that was overhung by a massive but seemingly stable ice cliff; the route seemed the better of two evils.

To my surprise, Paul decided to continue, even though he had no overnight gear. I arrived on a small saddle at 5,100m at about 3 p.m., dug a tent platform, and watched Paul slowly work his way up the steepening slope. The location was breathtaking: Rakaposhi and Diran to the south, Sangamarmar only a couple of kilometers east, and way in the distance the massive Hispar Glacier.

We both spent a sleepless night, Paul because he was lying in a large plastic pack liner, and me because I was so damn nervous. At 4 a.m. I brewed up, handed my sleeping bag to Paul, and headed up a steep snow slope to the first obstacle: a small band of granite covered in loose snow. I bridged up a gully for a few meters, had an “I can’t do this” moment, and climbed back down. Thwarted only half an hour from the tent! Taking a deep breath, I tried again and this time climbed the 20m to the top.

Another steep snow slope led to a 100m granite cliff. I headed right to circumvent it, then discovered I would have to traverse across a steep rock gully with a large drop beneath it, and so scurried back to the left. Above me were two ice cliffs, and between them a steep, narrow gully of snow. I front-pointed 100m up the gully and found myself in a wide cwm rimmed by huge ice cliffs 300m above.

The cliffs seemed quiet, but it was early, and I decided to climb onto a broad ice rib on the right of the cwm. I tried to hurry, but with snow almost up to my knees progress was glacial. Conditions were better up on the rib, however, and I sped up dramatically.

After climbing several hundred meters, passing some sizeable crevasses, I came to a large rock band forming the base of the summit pyramid. From base camp it had looked as if this could be navigated on the left, but now I realized this would require a long traverse over steep ice with a 1,500m drop beneath me. Far too scary! I accepted glumly that I’d have to drop 100m, traverse right under the rock band, and try to summit from the east side. The exposure was frightening, and with every step loose, wet snow swished down alarmingly, gathering speed until it shot over the ice cliffs. After what seemed like an eternity, the traverse ended and I was able to start climbing toward the ridgeline. By this time I was in the full sun and feeling tired.

At midday I hit the summit ridge above the east face. I could see the top, and the only obstacle seemed to be a 60°-70° ice slope. “I can rappel that,” I thought, and whizzed up the ice with renewed vigor. A five-minute wander along the final ridge put me on top. “Yippee! Now I can go down,” was my reaction.

Two raps off V-threads got me nearly down the ice slope, and another three off rock bollards saw me back to the start of the traverse. The snow had deteriorated further, and by the time I reached the broad rib at the far end I was in tears. But progress down the rib was rapid, and I soon cheered up. Back in the cwm, I sat behind a large block of ice, ate a bit, and started to feel pleased with myself. I set off again with a big grin.

Reversing the steep, narrow gully between the ice cliffs required concentration, followed by a nasty traverse back to the slope above camp. I spent 40 minutes cold-welding a stopper into a rotten crack for an anchor, and 30m later repeated the procedure to rappel the final rock band. I could see the tent, and soon Paul stuck his head out the door and waved.

I felt such an enormous sense of relief when Paul hugged me that I burst into tears for the second time. He had water and food ready. After 40 minutes he left to descend 1,000m to advanced base camp—another night in a plastic bag was beyond the call of duty! I fell sound asleep, and at dusk I woke, made another brew, and then passed out till 7 a.m. Descending the gully the next day, my legs were like jelly. Paul was waiting at ABC, and we packed up and made our way slowly back to base camp.