I've known about Scott Adkins for a long time. For a lot of martial arts movie fans he got noticed with the "Boyka" series of movies, which I've never watched (although I've seen some of the fights on YouTube). The movie of his that completely won me over was "Avengement:" Adkins is a decent martial artist, but he has a skill that almost no other martial artist can match. He can ACT. In "Avengement," he was an terrifying bundle of rage any sane person knew to avoid immediately after seeing him. Selling something like that - as well and as fast as he did, particularly given that he still allowed a core of humanity to show through - was amazing. And it guaranteed I would track down at least a couple more of his movies.
This and "Avengement" were both directed by Jesse V. Johson (as are several other of Adkins' movies - they're a good team, see "The Debt Collector"). In this case, Adkins is Mike Fallon, an assassin who specializes in making his killings look like accidents. We're introduced to the other assassins that drink at his pub/headquarters, and we see a couple of his kills. But his personal life gets tangled up in his business, putting him at odds with his own group. This leads to numerous brutal fights - an interesting feature of this film being the finest fight choreography ever seen in an Adkins film, by a wide margin (again keeping in mind I haven't seen the Boyka movies). Ray Park and Michael Jai White really helped, and I don't know who Amy Johnston is, but man she can fight.
The action is well defined, excellently choreographed, and brutal. The humour is almost as vicious as the action, and just as worthwhile - but you'll need a fairly strong stomach for both. I would say this sits about half way between "Avengement" and the first "Kingsman" movie - it's not quite as good as either of them, but borrows elements of both to make a very entertaining movie.