This movie could've been called enigma - in a positive way - a supernatural low-budget horror that takes thought to work out what's happening to who and why once past the half-way mark.
The story?
Five or six guys and gals from London go on a jaunt on the canals and watery inlets of Norfolk - think Everglades without the crocs - and slowly discover that as the movie straplines go, 'there's something in the reeds' and 'they can play tricks on you.'
Re what it is and why the guys & gals need to be worried we keep guessing, guessing some more, and the blood just keeps flowing.
Maybe there's too much guesswork for some but the lead girl pulls off the plot-moves passably well and the others make it a totally bearable experience, specially the first half of the movie.
My humble analysis is that 90% of people will like the first half of the movie, and only 50% will like the second: I liked it enough to comment and give a review but then I don't like movies with stars and nothing to say. This had something to say and even though it may have tied itself up in Gordian knots it's worth a 6 or 7.