Millennium Group consultant Frank Black (Lance Henriksen) faces difficulty when his sister-in-law is abducted after her son's baptism.
Spotnitz's script for "Sacrament", which he has called his favourite of those written for Millennium, draws inspiration from real life serial killers John Wayne Gacy and Dennis Nilsen.
Millennium Group consultant Frank Black (Lance Henriksen) joins his brother Tom (Philip Anglim) and sister-in-law Helen (Liz Bryson) for their newborn son's christening.
Fellow Millennium Group member Peter Watts (Terry O'Quinn) helps Black identify the kidnapper from a set of pictures of sex offenders from the Seattle area—Black recognizes Richard Green (Dylan Haggerty) as the man from the airport footage.
[3] Spotnitz was a prolific writer for Millennium's sister show The X-Files, receiving his first writing credit for that series for the episode "End Game".
[4] Spotnitz has described "Sacrament" as his favourite script for the series, finding the character of Richard Green to be "creepy" and believing that "the solution to the mystery [was] sufficiently unexpected".
[2][3][6] Watkins' work on the episode led to him becoming a director and executive producer for The X-Files when that series moved production to Los Angeles.
[16] Robert Shearman and Lars Pearson, in their book Wanting to Believe: A Critical Guide to The X-Files, Millennium & The Lone Gunmen, rated "Sacrament" three stars out of five.
Shearman felt that the plot was "a bit humdrum", finding that some emotional development was simply treated as "padding"; however, he praised guest star Philip Anglim for his performance.