River's Edge (1986)

Dir. Tim Hunter's controversial work is as powerful today as it was upon its original release. It follows a group of US kids, mostly of high school age, one of whom has murdered his girlfriend. The others learn of the killing, but their deep-seated apathy toward life means the crime goes unreported.
Thematically dark, for the most part, bordering on saturnine, the slow pace segues effortlessly from weird to quietly disturbing.
I've seen it likened to Richard Linklater's work, which is an understandable but not entirely helpful comparison. It made me think more of Marisa Silver's Permanent Record (1988), even though the two films deal with post-traumatic emotions very differently. Coincidentally, both feature Keanu Reeves.

4 grim triggers out of 5