Opening with one of the most arrestingly bizarre sequences in cinema this year - a woman with her head and hands cuffed in an outlandish S&M device drifts dreamily through an office performing the usual menial tasks of a legal secretary - Steven Shainberg's skewed love story is testament to the hoary observation that there really is someone out there for everyone.
In this case, the couple whose relationship we watch flower - and for whom we find ourselves rooting - don't engage with the usual romance movie cliches like mistaken signals, conflicting romantic entanglements or the inevitable 'failure to commit'. Instead there's the burgeoning realisation that their mutual love is best expressed through leather restraints and over-the-desk spanking sessions.
It's a daring idea, and one that could easily drift unintentionally into comedy or exploitation (and the crass tag line, "Assume the position!", is a step too far in the latter direction). However, Shainberg's deft direction keeps the prurience to a minimum and gives the whole thing a slightly surreal quality.
Meanwhile, Erin Cressida Wilson's screenplay (adapted from Mary Gaitskill's short story) effortlessly charts the shifting power relationships between Gyllenhaal (who needs the couple's unorthodox sexual expression, and gives Spader permission to play out his fantasies) and Spader (whose guilt about what they are up to threatens to derail their oddly tender relationship).
Both Gyllenhaal and Spader (for whom charting the extremes of sexual expression seems to be something of a vocation - see 'Crash', 'Sex, Lies, And Videotape' etc.) are on top form, with Gyllenhaal particularly effective.
A sub-plot in the third act, in which Gyllenhaal becomes something of a cause celebre and the focus of a media frenzy, is a misstep, deflecting our attention from the affectingly sketched relationship, and clodhoppingly attempting what is presumably meant to be some kind of social satire. But that apart, 'Secretary' is a quirky and unexpectedly heartwarming treat.