Casting for Scott Frank's A Walk Among the Tombstones continues to fill out around star Liam Neeson.  The adaptation of the Lawrence Block novel recently added Dan Stevens (Downton Abbey); we can now report that Ruth Wilson (Luther) and Boyd Holbrook (Milk) will also be joining the cast.  The story centers on private investigator Matthew Scudder (Neeson) who is hired by a drug lord in order to find out who kidnapped him and murdered his wife.  Hit the jump for more on A Walk Among the Tombstones.

Variety reports that both Wilson and Holbrook will be joining the crime thriller A Walk Among the Tombstones.  Unfortunately, besides Neeson, none of the other roles have been reported.  The following book description from Block's novel offers up a look at some of the other potential players in the story (via Amazon):

The wife of Kheran Khoury, heroin wholesaler, is killed after he haggles over the price of her ransom. With the help of two computer geniuses, a streetwise punk, drug lords and his friend, ex-cop Scudder, they track the killers through the back streets of Brooklyn.

It would be unfortunate to only see Wilson on screen briefly if she's playing the murdered wife, but perhaps Frank will work flashbacks into the picture.  Known as the enigmatic Alice on Luther, Wilson will next appear in Disney's The Lone Ranger and Saving Mr. Banks.  She was last seen in Anna Karenina.

Holbrook, meanwhile, is set to break out in a big way if The Host is anywhere near as successful as The Twilight Saga; both properties are the creations of author Stephenie Meyer.  He also stars in Terrence Malick's untitled picture and Scott Cooper's Out of the Furnace.