 Eva Birthistle plays Captain Kate Marshall , a " crack commando " who oversees Section 20 's military personnel . She and Stonebridge have an affair . The actress was taken by the script , and although she was cast for the role , she had not done action in her past acting career , and felt it would be a " fun experience " to play the character . When Birthistle went through military training , her goal was " just to keep up with everybody and not give up , pass out , throw up or cry . " Rhashan Stone plays Major Oliver Sinclair , Grant 's right @-@ hand man who helps her gather intelligence . Mealing called their working relationship as " very strong " and " simpatico . " Sinclair is the section 's second @-@ in @-@ command . Michelle Lukes plays Sergeant Julia Richmond , one of the newer recruits of Section 20 . Lukes describes her character as " exceptionally bright and technically brilliant , " with the ability to speak seven languages . Jimi Mistry plays the antagonist Latif , the terrorist mastermind behind Project Dawn . Richard Armitage returns as John Porter , the protagonist of the original Strike Back series , in the first episode . Originally , Armitage 's role in the series was not clarified when production was announced . In January 2011 , the Herald Sun reported he dropped out of the series because he would be playing Thorin Oakenshield in The Hobbit films . However , it was later reported he would return for the second series in a secondary rather than primary role . 
