The period drama will follow the true events following the assassination of President Lincoln at Ford's Theatre in 1865. Filming will start in October.
Wright Penn is cast as Mary Surratt, who was charged with conspiring to kill Lincoln. McAvoy will play Frederick Aiken, who defends Surratt and ends up believing that she is innocent.
McAvoy is rumoured to also be working on Wanted 2 with Angelina Jolie and director Timur Bekmambetov.