By Yashika Mathur Kochi, June 28 : Ace cinematographer Tanu Balak, who makes his directorial debut with the Malayalam investigative thriller "Cold Case", says they ensured adequate homework was done to make the probe procedure on screen seem real. "It's a very fast paced movie and there is no lag in it. People will be engaged in every manner. We did homework to make the investigation look real," he tells IANS. "Cold Case" stars Prithviraj as a cop and Adithi Balan as an investigative journalist who probe a death in different ways, only to discover the incident could have a supernatural undercurrent. "Prithviraj came into this movie because he had interest in the film. It was very comfortable to work with him," says Tanu, of working with the Malayalam star. Talking to IANS about shooting the film, he says: "It was a difficult task to shoot during the pandemic. We did all the introduction scenes first because it was safe that way, and the crowd shots at the end of the schedule." He recalls: "We had accommodated the crew in one portal. The characters took off their masks because they had to give the shots, otherwise everyone wore masks all the time. We didn't have any problem, we had all the protocols in place." The film, which will stream on Amazon Prime Video from June 30. /IANS