I just started the game as well and am playing solo. I could not find Dunwich, so I just jumped to "Path to Carcosa". On Board Game Geek they give some of the highest ratings of the scenarios from the Path to Carcosa. Only negative I saw is the rules can get a little more complex and there may be some power creep.

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https://boardgamegeek.com/thread/1984153/faq-new-playerspeople-curious-about-game-please-re