Endeavour is returning to ITV after the UK broadcaster ordered a second season of the Inspector Morse prequel.
The series debuted with a feature-length story in 2012 to mark the 25th anniversary of the original series and returned with four new episodes earlier this year.
Four new 120-minute stories have now been ordered, with production due to start later this year. They are likely to air in 2014.
Endeavour, produced by Mammoth Screen, stars Shaun Evans and Roger Allam. Writer Russell Lewis executive produces with Michele Buck and Damien Timmer. Camille Gatin is the series producer.