Information from Mountain Project (link):
Traverses the jagged skyline from Mt. Torment to Forbidden Peak. From the base of Torment, ascend the S. Ridge or the SE face (both loose 4th/low 5th class) to a prominent grassy ledge leading to a V-shaped notch climbers right. Packs can be left here as you summit and downclimb (or rap, though downclimbing is manageable) back, eventually following the grassy ledge to the notch. 
From here, a wild overhanging rap on obvious slings takes one to the snow traverse on the North side [The entire traverse can be completed on rock, mitigating snow travel]. Traverse steep (50-55 deg)and crevassed (heavily in late season) snow/ice across rock ribs to the major rock ridge. From here, either a continuing snow traverse on the North or grassy 3rd class ledges on the South lead one to the beginning of the knife edge traverse. 
This continues, past the 'sidewalk in the sky'- an aptly named flat section of ridge where exposed downclimbing (?) or a single rappel takes you to the obvious notch at the beginning of Forbidden Peak's West Ridge. This classic route is followed to the summit, via 4th/5.easy terrain to a 5.6 tower pitch, then further to the summit. Downclimbing and rappels take one back to the notch, where the standard Forbidden peak couloir/gullies can be descended (downclimbed/rapped) back to the glacier, and back to Boston Basin (don't cliff out on the waterfall slabs!- go skiers left (?)).

From SummitPost.org (link):
The traverse from Mount Torment to Forbidden Peak is a suberb yet moderate alpine route that will demand the use of every mountaineering skill you've learned. All but the most confident rock climbers will do at least one rappel, probably more. Although the route-finding follows a simple heuristic--when if doubt, drop down on the north until you find a way--there are many small route-finding decisions to be made along its length that will have a cumulative effect on your time, exposure, and overall experience. Easy glacier travel is involved in the approach, and steep snow (ice later in the season) skills are mandatory. Perhaps the most important skill required is the ability to move rapidly and confidently on exposed fourth class terrain. Lots of it. The route is a mile long, and there there are only a handful of places where a fall wouldn't be serious, if not fatal. 

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Planning info to come...