The programme notes helpfully define a cryptogram as "A piece of cryptographic writing; anything written in cipher; or in such form or order that a key is required in order to know how to understand and put together the letters".
David Mamet's challenge to his audience in this play, originally seen a dozen years ago just around the corner at The (New) Ambassadors, is to find that key.
In Josie Rourke's production, the underlying style combines Beckettian existentialism with kitchen sink drama, not always comfortably.
The speech patterns are naturalistic and the action minimal, as we try to decipher little throw away mysteries in an otherwise normal scene of domestic harmony, set in Chicago in 1959.
Peter McKintosh's design of a family home sets the tone if not the period, with a plain living room reflected in a shiny black back wall and an impossibly long staircase comprising 23 steps rather than the usual dozen or so. The lives portrayed are similarly reflective and mildly imperfect.
The natural assumption that the trio before us are parents and their precociously intelligent son is misleading. In fact, the man, Del played by Douglas Henshall, is some kind of family friend but it takes time to understand the relationships fully.
By process of elimination, this means that the father, Robert, is missing, but then who is Del? The little boy John, played on this occasion by Oliver Coopersmith, adds to this sense of unease with his own disquiet and a questioning nature.
This is a place of inconsistencies that could is easily come from a Sam Shepard play as one by Mamet, although Shepard generally injects more madness. Gradually, clues build up and uncertainties are cleared, particularly when a note is discovered announcing that Robert has left his attractive wife Donny, played by Sex and the City's Kim Cattrall.
Perhaps Mamet sums up his theme in the line "At some point in our lives, we have to face ourselves" and his concentration on the need to propitiate ourselves for wrongs committed, either deliberately or unwittingly.
Although there is little action, all builds calmly to the relative drama of Donny's temper tantrum directed at innocent John and her damning dismissal of Del, whose good natured simplicity almost borders on a minor case of autism. The final image is also strikingly sinister.
At only just over an hour, The Cryptogram has the feeling of a curtain raiser rather than the main feature and there is a risk that those who are not blinded by the chance to see Kim Cattrall and/or Douglas Henshall in the flesh may feel short changed.
The acting is fine and Oliver Coopersmith may only be ten or eleven but easily lives with the stars. The writing contains some interesting ideas but really, this play should have been paired with another complementary piece to offer a full evening.