Death in Paradise just gave us one of its greatest-ever episodes — and Don Gilet deserves a lot of the credit

Death in Paradise season 14 episode 7 will go down as one of the show's best-ever episodes largely due to Don Gilet's brilliant performance as DI Mervin Wilson.

The 58-year-old joined the cast at Christmas and ever since the long-running BBC hit has felt like it's been building up to something great and episode 7 saw it deliver on that promise. I will certainly be adding it to our best Death in Paradise episodes list.

Initially, when Mervin turned up on Saint Marie he came across as just a bit of a grouch who enjoyed taking a swipe at the island whenever he could much to the frustration of his colleagues.

But slowly we learned about Mervin's past and that he was on the island to find his mother, Dorna Bray (Judith Jacob). Discovering she had died, he then started to suspect she'd been murdered and in episode 7 he set about finding her killer. I won't spoil what happened but Don gives a superb performance, giving real depth to the character and making this normally gentle series very emotional especially when he discovers Dorna's true feelings about him. Imagine never knowing if your mother loved you or not and then finally finding out.

But it was more than just that. The whole episode felt like a series back on song. At times Death in Paradise has been drifting along merrily in the Caribbean, enjoyable enough but perhaps not reaching the heights it once did. Personally, I fell in love with the show right at the start, with Ben Miller's grumpy DI Richard Poole and Mervin is certainly like Richard in many ways.

What makes a good Death in Paradise episode?

There's the essential question of what actually makes a great Death in Paradise episode? Well, firstly you need a good murder mystery. And episode 7 certainly gave us that. How on earth could Mervin's mum have been murdered when she went out to sea on her own in a boat during a storm? In a nice twist, the episode switched up the normal format of the detective having four or five suspects, to instead having just one, Roy Palmer (Gerard Horan). But was Mervin right or could someone else have done it?

Secondly, Death in Paradise thrives on humor, and in between all the emotional scenes, the episode had a lot of laughs mainly provided by Sterling Fox, The Commissioner's replacement. There was a nice early scene where Naomi spots Sterling and says: "Oh no, please not him." When hearing Sterling's going to be in Saint Marie for the next few days, Mervin quips: "Well, aren't we the lucky ones". But the funniest scene occurs after Sterling shuts down Mervin's investigation.

Selwyn, fully dressed back up in his Commissioner's gear, marches up to Sterling outside the police station and promptly arrests him for criminal damage to his car, thus giving Mervin a chance to find his mum's killer. Sterling has been a great addition to the show and I hope we see more of him.

Thirdly, Death in Paradise needs a great support cast and one of the beauties of Don Gilet's performance is it's lifted the rest of the cast. Shantol Jackson's character Naomi has become more interesting now she can react to Mervin's rudeness and the pair have a spark. We should mention that guest actor Gerard Horan, best known as Terry in the comedy Detectorists, also gave a fine performance as Roy Palmer, leaving you wondering right until the end what his true motives were.

Death in Paradise has been a remarkable success, but to survive it needs to reinvent itself and thankfully for fans Don Gilet's arrival has given it new life and purpose.

We can't wait until the season finale, although on that note it's been delayed a week due to Comic Relief airing. Instead, it will air on Friday, March 28. And it sees Mervin prepare to fly home when a body is found in the shack making him a possible suspect...

Death in Paradise season 14 and the past seasons are available to watch now on BBC iPlayer. You can watch the series in America via BritBox.