Dead Reckoning (S03E04)

Title: Dead Reckoning Plot: A covert agent is brought to Britain under strict secrecy, but his homeland associates in Bulgaria seem intent on exposing his every move. Shortly after his arrival, he is found dead, leading CI5 to investigate the circumstances surrounding his murder. Their suspicions fall on his daughter, a music student, who may have had a hand in his demise by administering poison. As the investigation unfolds, the truth behind his killing and the motives of those involved come to light.