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DCI Vera Stanhope finds herself investigating both sides of the thin blue line in order to find the killer of a brilliant young police officer

Alan and Paula set up a mediation scheme for subpostmasters to use to apply for compensation but James Arbuthnot MP publicly accuses the Post Office of sabotaging it

At the Royal Courts of Justice, Alan and his friends give evidence on behalf of their army of 555 subpostmasters. Drama, starring Toby Jones

Secrets could be exposed as Rosamund arrives at Downton following Edith's shock departure, while Isobel makes a happy announcement - but there may be trouble on the horizon

A man incarcerated for the murders of three police officers launches an appeal when the evidence is called into question - and then another officer is killed

A businessman on board the Orient Express asks fellow passenger Poirot for protection, but is later found dead. Hugh Bonneville and David Morrissey guest star