In the five years between The Bourne Ultimatum and this new addition to the franchise, ideas in all stages were being thrown around in the hope that a fourth film would eventuate.

It didn't matter that Robert Ludlum's original trilogy was finally complete on screen; the success of Ultimatum had propelled Hollywood bigwigs to try and keep it going to perhaps rival the spy of all spies, James Bond.

When director Paul Greengrass pulled out of the project in 2009, unhappy with its progress, so too did Matt Damon. Trilogy screenwriter Tony Gilroy had a job on his hands - but rather than continue with the ideas presented in the books continued after Ludlum's death by Eric Van Lustbader, he created something completely different, only taking the name of book number four.

Aaron Cross (Jeremy Renner) is an agent in the Outcome program, one of a number directly affected by the allegations made against the CIA that form the bulk of Ultimatum's story. Confused? It runs as a side-story to those events, often referring to the hunt for Jason Bourne as CIA Deputy Director Pam Landy (Joan Allen) goes head to head with top dogs like Noah Vosen (David Strathairn) in the courtroom.

Aaron is a target after escaping assassination and gets Dr Marta Shearing (Rachel Weisz) on his side with the hope she can wean him off his program medication permanently, which affects his physical and mental ability (to sustain the action-packed lifestyle of being on the run, etc).

The bulk of the film is based around this event, and while questions are answered it takes a while to get there.

Gilroy's screenplay with brother Dan is smart, correlating with the events of Ultimatum nicely.

Scenes from that film are linked in seamlessly in relation to talks previously behind closed doors, where Retired Colonel Eric Byer (Edward Norton) is approached for help by CIA director Ezra Kramer (Scott Glenn). As the new kid on the block, he gets a heavy task of having to decide who dies.

But a stretched beginning draws out the few real events of the film and reveals a lack of depth with the overall plot.

Aaron is fleshed out enough to reveal why he chose to involve himself in the program but it hardly feels complete; some mystery should remain, yes, but what gives him the real drive to do what he does is questionable.

Thankfully, the action sequences largely make up for this. As arguably the highest expectation in the lead-up to its release, Legacy gives us one hell of a chase.

The camerawork from Robert Elswit is frenetic, often to the point of exhaustion, but maintains that fast pace to reiterate the urgency of the situation.

As a director for the first time in the series, Gilroy keeps the overall pace much the same, making use of the great Alaskan landscape as well as the bustle of Manila to take it international.

Renner can fit the bill as a new potential hero, effortless in a street fight and persuasive in conversation. Weisz and Norton also do well to fit into the mould, while the return of much of the original cast is comforting. It does hold up to the legacy, but to establish a new hero takes time.

Rating: 3/5

Now screening at Reading Cinemas