This is a 2012 British-Irish drama directed by James Marsh, based on the novel of the same name by Tom Bradby.
Although it is a hard-boiled, apparently good spy drama, there must be a script deficiency because the storyline is too ill-contrived for me to understand---especially for the last part, which leaves me puzzled and unsatified.

Boring. Skip it.

Glad I watched it (finally - almost returned it without doing so). Good acting, story, etc. The historical Ireland/Northern Ireland split is compelling.

I also was glad for subtitles - although I've been to Ireland a couple times. The way they pronounced quay (a wharf) as kei was surprising, but I see wikipedia gives it that way, too.

First-class acting and an excellent screenplay. The build-up of the relationship between Clive Owen and Andrea Riseborough is terrific. Don't miss it.

How twist does a twist ending have to be, and how logical?

I think this is a pretty good film on the IRA conflicts of the past. Be prepared for an ending which is totally unexpected. For me, anyway.

Rated 5/10.

Wonderful actors performing their parts well. Still surprised by the surprise at the end even though viewers should expect it as agent Mac refused to stop digging into the past.

Rather boring.

Decently told story of the attempt to turn an IRA member into an informant. Clive Owen effective as MI5 agent. Surprise ending.