Both the book and each print are signed.

Threshold is built around images of empty interiors bearing traces of former human presence, furniture impressions, wall marks, shadows left behind by things that once occupied a space. The visual language is dense and repetitive, with a near-monochromatic, geometric-abstraction feel that critics have compared to Ad Reinhardt or Rothko; some image pairs are sequenced to create an "uncanny dialogue" through subtle variation. Conceptually, doorways and thresholds recur as literal and metaphorical passages, inviting a room-to-room reading that one reviewer (Brad Feuerhelm, on ASX) linked to the "backrooms" idea of liminal, endless space.

The book itself is considered a strong piece of design as an object in its own right, in the tradition of Michael Snow's Cover to Cover.