This is one of the most beautiful hikes in Verzasca. You start in Gerra, near the church and follow a steep forest trail up for about 30min. This is when the hike starts getting interesting (and never stops until the very end), you have wonderful views across and down the valley with its towns (Frasco, Sonogno). At the same time, the trail itself passes through breathtaking scenery, taking you through small groups of rusticos (especially in the first part of the hike), slopes covered with huge boulders and wild waterfalls. You never really get all the way up to the peaks on this hike but rather you follow the rim in the higher sections of the nearby mountains. Once you initially get up to 1700m (after about 2h from Gerra), the hike is rather flat for most of its duration letting you concentrate on the incredible views. At the highest point the trail goes up to 1950m and then slowly descends to 1720m at Alpe della Mugaia. At this point you start the descent towards Puscen Negro (at 1340m), a beautiful little village high above Sonogno. The village is absolutely worth a look (the trail misses it by 50m or so). The way down to Sonogno then takes only around 45min. Once in town, you can take the bus back to Gerra or take a nice walk back (you'll need to add at least another 1h or so).