This is Shirley Henderson's film through and through. If "Frozen" does nothing else it must surely let casting agents see that Henderson can be stretched further than we have ever seen before and that she will deliver the goods. Her performance has already been recognised in the BAFTA Scotland Awards in 2005 where she (rightly) picked up the Best Actress prize. This is the first time that she has carried a film as the star that she is. Here there are no places to hide since she is on screen in mostly every scene. With a flawless Lancashire dialect (she is Scottish) and a paper-thin fragility, she convinces us that she is trapped in this bleak but beautiful (and rarely filmed) place as she searches for the truth behind her sister's mysterious disappearance.
The film is slow though well paced, stark and bleak, but never dull, but would have been a whole lot better if the end wasn't so obfuscated and needlessly confusing. In a whodunit (and this is) you can't short change the audience by not telling them what happened. From what I can tell, about half the audience when I saw it really liked the film. Others were disappointed and without doubt this is not a commercial film by any standard, but it is one worth seeing just for Henderson's tour de force.