There's a big difference between "simple" and "simplistic," especially where indie horror films are concerned. There are countless rotten movies that have elaborate (or even clever) ideas, but hit the screen in very simplistic fashion. Conversely, there are calm, quiet, and unexpectedly compelling little thrillers like Solo, which don't boast a whole lot in the plot department, but use a simple premise to deliver a tight-fisted and intense little experience. And who needs all that extra story junk when simple works better?
Solo is about a young woman is none too thrilled about heading off to be a counselor at a summer camp, but unhappy Gillian (an excellent Annie Clark) seems resigned to make the best of her hardships. Oh, but before she can actually join the staff, Gillian must spend two nights alone on an isolated and creepy (but allegedly safe) little island across the river. Writer/director Isaac Cravit lays down some low-key but effective character development with Annie, we quickly get a sense of her "moody, but for good reason" perspective, we get to the camp, and then the island -- and then, of course, some form of overt threat makes its presence known.
And that's where Solo becomes a sparse and effective survival thriller that (if you pay attention) also manages to work as a nifty little whodunit. (Hint: pay attention to Gillian's new boss back at the camp.) Yes, Solo is one of those dreaded(?) "slow-burn" indie thrillers, but one fails to see how that's a problem. If you want a slash & splat film, the virtual shelves are full of them. If, however, a well-made, low-budget indie film about a moody young woman who goes from troubled to lonely to terrified to resourcefully angry sounds interesting, Solo fits the bill nicely.
Those who approach Solo expecting a powerhouse horror film or a fast-paced desperate chase like Deliverance may not appreciate what Cravit and company have to offer, but as a mellow and gradually suspenseful thriller that pays more attention to restraint, location, and character than to predictable shocks, typical story beats, or unnecessary gore, Frankly not a whole lot "action" takes place in Solo, but what's on the screen is rather quietly intense and engaging.