Here's Rossiter's description on mountainproject.com:
This ultra marathon spans (counter clockwise) the entire rim of Glacier Gorge traversing 8 summits in perhaps 15 miles. The 7 towers along the Keyboard of the Winds are not climbed. Begin at the Glacier Gorge Bus Stop. Take the Glacier Gorge Trail and ascend the Regular Route on Thatchtop. Traverse the summit and gain the Continental Divide via the Northeast Ridge of Powell Peak. Traverse Powell Peak and descend into McHenrys Notch. Climb east out of the notch (5.5, 300 feet) and traverse McHenrys Peak (Northwest Ridge/Stone Man Ridge), Chiefs Head Peak (Northwest Ridge/East Ridge), Pagoda Mountain (Northwest Face/East Ridge), Longs Peak (Southwest Ridge/Keyhole Ridge), Storm Peak and finally Half Mountain. Descend a talus gully on the northwest side of Half Mountain and regain the Glacier Gorge Trail at Mills Lake. Run the final 2.5 miles back to the GG Bus Stop. This is a very long and demanding circuit with various challenges beyond sheer endurance such as the Northeast Ridge of Powell Peak, McHenrys Notch, the Northwest Face of Pagoda Mountain and the south ridge of The Dark Tower. The descent of the Keyhole Ridge is not trivial. Best time to date: 13 hours, R. Rossiter, 11 August 2009. I am just an old guy. Someone younger and faster could probably do this in half the time.