Mumbai Mar 21 PTI Actor Ajay Devgn says whenever he decides to direct a film he constantly searches for challenging subjects which excite him as a makerDevgn made his directorial debut in 2008 with the drama U Me Aur Hum and followed it up with his 2016 actioner ShivaayThe actor is currently awaiting the release of his third directorial Runway 34 billed as an edge-of-the-seat thrillerDuring the trailer launch of the film on Monday Devgn said he was fascinated by the story when writers Sandeep Kewlani and Aamil Keeyan Khan approached him more than two years agoInspired by true incidents Runway 34 revolves around Captain Vikrant Khanna played by Devgn a flying prodigy whose flight takes a mysterious course after take-off from an international destinationI really wanted to make the film as I was fascinated by the story When we began work it started to shape up very well and within a month we went on floorsWhen I want to make a film I search for films which are not easy to mount So it was difficult to create new visuals as the film is set on ground and on air But it was also exciting the 52-year-old actor told reportersThe actor said he first came onboard the film as a director and then decided to also star in it Eventually he also decided to back the project under his banner Ajay Devgn FfilmsRunway 34 also features megastar Amitabh Bachchan Boman Irani Rakul Preet Singh and Angira DharDevgn said he was certain to cast Bachchan for the film and had no other casting optionIn this film for Mr Bachchans role if he wouldnt have agreed I dont even know if I would be able to cast any other actor I dont think I would be making the film he addedDevgn said he had earlier directed a schedule of his film Major Saab with the 79-year-old actor when its director Tinnu Anand fell illBut this is the first time I worked with him in a full-fledged film as a director Ive known him ever since I was a child I would visit his set often Later I went on to work with him in nearly six films To say anything about him would be a cliched because I havent seen any other hardworking professional actorThe energy and dedication he works with is amazing Even if he is facing any problem once hes on set he forgets everything I feel inspired to do better work when I look at him he addedThe film is co-produced by Kumar Mangat Pathak Vikrant Sharma Sandeep Harish Kewlani Tarlok Singh Jethi Hasnain Husaini and Jay KanujiaRunway 34 is scheduled to release on the big screen on April 29 PTI JUR BK BK