Grace solves long-standing mystery in tragic season finale

However, it happened in a devastating way, and when all was said and done, the detective lay crying in the arms of his pregnant fiancée Cleo.

The beginning of the episode picks up where the last one ended: Roy and Cleo visit Sandy in a hospital in Munich. Roy initially goes to her alone, but her answers about her disappearance make him angry.

Sandy admitted that she had become unhappy in her marriage because his obsession with his work and his cases had gotten the better of her and she felt she could not contact him.

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Feeling she needed to build a new life for herself, she fled – intentionally leaving Roy to believe she was dead.

Roy stormed out angrily before Cleo persuaded him to go back inside with her.

When the topic of children came up, Sandy winced, saying that Cleo would have a hard time raising her children since Roy spent so much time at work.

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Roy said it was a good thing that he and Sandy never had children together, and he and Cleo returned to Brighton together feeling they had found some closure.

However, a devastating phone call at the end of the episode completely devastated Roy. It turned out that Sandy had committed suicide and left Roy a letter telling him that she loved him and that she hadn't been happy for a long time and didn't see a way forward for herself.

She also revealed some explosive news – she was pregnant when she left him, and the paternity test she took Roy's hair for in season 3 was clear. He is the father of an eight-year-old boy named Bruno.

She asked him to keep an eye on Bruno, which will almost certainly be a major storyline in Season 5, in which Roy meets the son he never knew existed.

It was a tragic end to Season 4, and it also looked like it might end with the death of Norman Potting when Craig Parkinson's character went undercover.

However, he came out alive and was last seen with the team celebrating their successful case – so it's likely that Parkinson only decided to leave the series after filming for season 4 and we'll find out what happened to his character in the first episode of season 5.

You can buy Peter James Roy Grace's books adapted for Season 4, Dead Man's Time, Want You Dead, You Are Dead and Love You Dead, now on Amazon.

Seasons 1-4 of Grace are available to stream now on ITVX.

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