SAAHO is the story of a mysterious man on a mission. The foreign city of Waazi is ruled by gangsters and criminals and the biggest of them is Roy (Jackie Shroff). He cleverly manages to get the approval of an Indian minister, Ramaswamy (Tanikella Bharani) for a hydro project in India. He then reaches Mumbai and this is where he's killed in a road accident. His son Vishwank (Arun Vijay) then takes over, which angers Devraj (Chunky Panday) as he wants to sit on Rao's throne.
Meanwhile the Mumbai crime branch is investigating the death of Roy and other related crimes. The case is handed over to Ashok Chakravarthy (Prabhas), a macho and extremely intelligent officer. He insists that Amritha Nair (Shraddha Kapoor) is also made a part of his team after he gets smitten by her photograph. While scanning the CCTV footage, they come across a mysterious person (Neil Nitin Mukesh) who they believe is a suspect. In the absence of evidence however, he can't be arrested.
Ashok however manages to speak to him and finds out that he's hunting for a black box which can be used to access the wealth left by Roy in Waazi. Not just this chap but even Vishwank is trying to find the black box, which is hidden in Mumbai. He sends his associate Kalki (Mandira Bedi) who for some reason secures the box but instead of taking it to Waazi, she deposits it in a bank.
When the mysterious person comes to get it, the cops who are already on his trial arrest him. However, the cops get a shock of their lives at this point when they realize they have a mole in their team. The mole runs away with the black box and this baffles not just the police force but also the gangsters of Waazi. What happens next forms the rest of the film.