Wrath of Man

Very simple story- don't kill my son. But beautifully executed. H is a rich bad guy who's son gets killed when H was doing some odd jobs he wouldn't do as the Boss man. What follows is a few months of multiple homicides. It gets more and more violent until H realises he has to step into the shoes of the victim of the crime where his son was murdered to find his killers because they will strike again. So he becomes a security officer who guards cash vehicles. And of course with his taste in violence he easily wows his colleagues. Waits and soon enough the ex-US army sergeants who are just sitting around twiddling their thumbs in odd jobs strike again, harder. Most of them die, and finally when H finds the bad guy, so does he after reading aloud his son's autopsy report. 

Very gory, but very cleanly executed. Brother has definitely developed a thing for Guy Ritchie movies it seems