(Cover) - EN Showbiz - Tom Hanks is happy with the way his newest film addresses "serious" subjects.

The 55-year-old actor stars in upcoming drama Extremely Loud and Incredibly Close.

The film follows a child's mission to find a mysterious lock that matches the key his deceased father, portrayed by Tom, left him before he died at the World Trade Centre on September 11 2001.

Tom is happy to be covering such significant subjects in this movie.

"In a lot of ways you can say that this movie was 10 years in the making because it deals with the individual details of what was probably the most serious day in all of our lives," Tom told ET Online.

"Part of the test that this screenplay had to pass was whether or not it held up, and just the verisimilitude on one hand, but also does it have the weight to warrant the movie being made in the first place? And I felt that it did."

Tom was deeply impressed by his 13-year-old co-star Thomas Horn's performance in the film. He felt the teenager's portrayal was exceptionally authentic.

"He's an extraordinary kid in that he was willing to do it in the first place," Tom said. "I don't think he has any dreams - he's not like a kid who goes to bed every day thinking about show business - and yet he was willing to open himself up and come in and not just fake the behaviour, but create the behaviour that was going to be necessary."

Extremely Loud and Incredibly Close will be released across the US in January. (C) Cover Media