Upstream Color (2013)

Upstream Color is one of the most inventive films on this list, but it's also a bit dull, and you'll need patience. It's built around a parasite passed between people, pigs and plants, which controls how its hosts behave. That sounds absurd, but parasites that change their hosts' behaviour really do exist in nature, so the core idea is more grounded than it first appears. The trouble is that the film is so fragmented and dreamlike that it's hard to stay invested. I admire it more than I enjoy it.