Director Nicolas Prividera searches for answers as documentarian, as an Argentinean, and as a son in this unflinching look at a nation's painful history. M follows Prividera as he searches for answers as to why his mother became one of Argentina's infamous "disappeared" when he was six years old. Confronting the political militancy that swallowed up his nation in the 1970s, as well as his own unresolved confusion and rage over the loss of his mother, Prividera interviews family, friends, and comrades with open desperation about long-held questions for which no satisfying answers may exist.
~ Cammila Albertson, All Movie Guide