It's easy to imagine the pitch for HBO's polygamist drama, Big Love: Everything a normal family faces, times three. It's a neat formula, and it captures much of the pleasure of the series, which centres on the ever-expanding family of the Utah businessman and polygamist Bill Henrickson and his three wives, Barb, Nicki and Margene - a family which, for all its complications, faces the same challenges as any normal one. But simultaneously it misses the show's underlying tension, the uneasy question of how the viewer should understand the dynamics of this unconventional ménage. Are the Henricksons, as they themselves believe, a happy, well-adjusted family unit? Or is there something fundamentally unhealthy, even abusive, about the arrangement?

In the first season, these questions were largely sidelined. Instead, the Henricksons were depicted as being close to the ideal American family, albeit one defined by the secret which separates them from the norm. This was reinforced by the contrast between their lives and those of their fellow-believers in the Juniper Creek community, headed by the reptilian Roman Grant. But in the second season, their apparent normality begins to dissolve. As Bill pursues his campaign to oust Roman, uncomfortable parallels begin to emerge between the Henricksons' relationships and the multiple marriages of Juniper Creek. Likewise, when Bill begins courting a waitress, we are forced to question whose needs and desires his marriages really satisfy. And, as Bill and Barb's teenage children grapple with the competing demands of the outside world and their largely hidden home life, we see the damage Bill's beliefs wreak on those with no choice but to follow his lead.

The net effect is often profoundly unsettling. Like The Sopranos - a series to which, in its almost seamless juxtaposition of the quotidian and the inward, secret world within the most ordinary of lives, it owes more than a little (in one memorable scene, Bill's son Ben is initiated into the priesthood in a basement lined with bulk groceries) - Big Love plays a complex game with its audience's sympathies, asking that viewers empathise with these characters, even as they are forced to question what exactly it is they are empathising with.