DeKok and the Mask of Death

Women are checking in to Slotervaart Hospital, but not checking out. According to hospital files, they were never even there. Inspectors DeKok and Vledder are called upon to investigate this alarming disappearing act.
Eerily, the people closest to these vanishing women all comment on a change in their faces: they have become listless, fatigued, and seemingly wear a 'mask of death'. All indications point to foul play, but the bodies have yet to turn up.
DeKok is stumped as to how these women are connected, and why an esteemed hospital is playing cover-up...