In NDPR, Gary E. Aylesworth reviews
Andrew J. Mitchell's The Fourfold: Reading the Late Heidegger
On Mitchell’s reading, the danger lies in the one-sidedness that comes about through the forgetting of being as the medium of appearance (the world), so that “beying” shows itself only as positionality. However, humans stand in a more original relation to being, and can therefore never become standing reserve without remainder. In them, "a trace of the thing persists", and the fourfold is Heidegger’s attempt to recover this trace in the midst of positionality.
This is one of the two must-read
books on Heidegger this century.