SCOTTISH actors Brian Cox and Julie Graham will join the cast of BBC One drama Shetland as it returns for a second series.

The show, starring Douglas Henshall as detective Jimmy Perez and based on the novels of Ann Cleeves, has been re-commissioned for six episodes.

Cox will play Magnus Bain, an outsider who finds himself at the centre of a murder investigation, while Graham stars as procurator fiscal Rhona Kelly.

The plotline will focus on the three remaining books from Cleeves's quartet: Raven Black, Dead Water and Blue Lightning. Filming is currently under way at locations in Shetland and elsewhere around Scotland.

Graham said: "I'm delighted to be joining Dougie and the rest of the cast as a new returning character. It will be lovely to be back filming in Scotland."

Shetland, made in collaboration with BBC Scotland and produced by ITV Studios, attracted a combined audience of more than 12 million viewers when it was shown on BBC One in March.

Elaine Collins, executive producer, ITV Studios said: "We have an extremely strong line-up of writers and directors this year and are all looking forward to returning to the compelling and unique landscape of Shetland."

Christopher Aird, head of drama for BBC Scotland and executive producer, added: "I am thrilled the likes of Brian Cox and Julie Graham will be joining the cast."