The expansion of the EU and open borders in the UK have led to a surge in foreign criminals heading for Britain. The number of requests for wanted fugitives has risen ten-fold over the past five years and now totals more than 4300 a year.

Over the course of three months Cutting Edge has unique access to New Scotland Yard's Extradition Unit as they track down murderers, suspected rapists and armed robbers from abroad.

A record 1500 foreign fugitives are now arrested each year and with more and more coming to these shores it's a job that is stretching the unit and its officers to the limit.

Some of these criminals go to extraordinary lengths to evade capture, changing their name and ID, so it's a painstaking and often frustrating experience tracking them down.

The film-makers are there as officers follow up on leads tracing potentially dangerous criminals, and capture high-tension arrests as the unit's hard work finally pays off.

The cameras are also with the unit when it deals with some of its biggest ever high profile cases, including the arrest of Wikileaks founder Julian Assange, wanted in Sweden for alleged sex crimes, and the arrest of Shrien Dewani, wanted in South Africa in connection with the death of his wife, Anni, on their honeymoon.

Other cases include the hunt for Hungary's most wanted fugitive, a Turkish man who conducted an honour killing, a suspected Croatian war criminal and an alleged serial rapist who's escaped the French authorities and who they must close in on before it's too late.