This lake?
http://northernwilderness.net/lakes/sesikinaga
It connects to Jeannette Lake via a small inflow. I've fished Jeannette (via Kabeelo Air) four different times and am going back there this summer. The area got hit very hard with forest fires last year, so Jeannette and Sessi were closed off for a while. The cabin on Jeannette actually burned down and we got redirected to a different lake (Okanse, which is also served by Northern Wilderness). It is possible that there are some burned down woods on part of the lake, but I doubt that affects the fishing.
Excellent walleye fishing on Jeannette, and I would have to imagine Sessi is very good too. Average walleye are about 18 inches, and we have caught them up to 31 inches. Have caught northern in the low 40's but we don't target them as much.
From the map, it looks like a lake you could easily get lost on without a GPS, though it's not big enough where you'd truly get lost like LOTW. My experience with the lakes in that area is that you don't need to worry about gathering all the hot spots in advance. These lakes are LOADED with fish, and if you have a basic knowledge of vertical jigging, you'll be fine. Your outfitter should be able to point you in the right direction to get started.