A mysterious assassin kills political agitators in order to divide revolutionary and reformist factions within the miner's trade union. The ghosts of the assassinated wander the desolate landscape of the mining district in search of an explanation for their demise (physical & political).
As that synopsis might suggest this is an amazing film - a mix of film noir thriller, ghost story, Brechtian social realism, Cocteau-inspired surrealism and Antonioni-style existentialist angst, with a great avant-garde soundtrack "directed" by Takamitsu. Overall, the mix works very well, similar to other Japanese New Wave movies (especially early Oshima), with elements that made me think of many other films, from Schrader's Blue Collar to Wenders' Wings of Desire.
Because the film has political & historical depth, I found Pitfall much more interesting than Teshigahara's better known 60s cult period-pieces Woman of the Dunes & Face of Another (where "pop" style & allegorical contrivance became overwhelming).
This DVD edition is excellent, with a detailed booklet & informative audio commentary from Tony Rayns, explaining how the film evolved slowly out of prior radical theatre & television versions in the context of revolutionary events surrounding the Japanese political crisis of 1960.