Bipasha Basu debuted with 'Ajnabi' (2001) directed by Abbas-Mustan. The film was a thriller and also starred Akshay Kumar, Bobby Deol, and Kareena Kapoor. 'Raaz' (2002) was her breakthrough horror film, and 'Jism' (2003) and 'Omkara' (2006) came later. The question asks about her first film, which is indeed 'Ajnabi'.