Zafar Younis joined Section D in the series 3 episode "The Suffering of Strangers," when MI5 officers Fiona Carter and Danny Hunter are being held hostage by terrorists. Zaf is an MI6 officer who had worked with Adam Carter (played by Rupert Penry-Jones) before Adam transferred to MI5. Zaf assists in saving Fiona's life, but Danny is killed by the terrorists. With Danny's death, Adam asks Zaf to join Section D.