Cleddau was not without its faults. But the latest Welsh crime drama on S4C had enough to entice viewers back for more. Each new addition to the Welsh-language channel’s catalogue needs to bring something new, fresh and exciting, such is the proliferation of the genre since Y Gwyll / Hinterland. And while there are well-trodden tropes in this latest series, there are also moments of nail-biting tension, surprising twists, and interesting character portrayals.

Elen Rhys plays Ffion, one half of a detective duo whose fairly unique quirk is that they used to be an item. Before Rick, played by Richard Harrington, had an affair with nurse Helen (Rhian Blythe). Ffion left in the aftermath, but returns a decade later to help solve the case of a copycat murderer. The two are paired back together, and there are no surprises as to how their relationship develops. But despite this stereotypical storyline, it is used to good effect to portray Rick as a rather manipulative and controlling character. Themes of trust and truth play out between the two but spread into the lives and stories of other characters around them. Including the man charged with the original murders, Paul Harvey, played with cold, calm villainy by Ian Puleston-Davies; and his wife Anna (a deceptively vulnerable Eiry Thomas).

There are elements of Sherwood and The Killing in its carousel of potential suspects from a close community all-too-familiar with original events. Both Gwydion Rhys (as Ryan Moss) and Matthew Aubrey (as Mel Owen) give excellent, if not highly conventional, portrayals of troubled men accused of the latest killing. Such typical character types offer nothing novel. Just as the shots of Jamie Tilston (Sion Alun Davies) beforehand spoil the on-screen revelation of his real identity. However, scenes like the school shooting in episode two, the showdown in the cellar and everything that comes before it in the final episode, ensure that Cleddau maintains the interest and excitement of the viewer. It is these sections that offer up real suspense. And as the series edges nearer to revealing the killer, threading all the characters together to build real tension, one feels validated in sticking with it through the less intriguing stuff.

For all its flaws and predictability, Cleddau also has its fair share of the edgy and enthralling. It is a shame that such moments are not too many to make this series a real thriller. But it is a crime drama with enough unexpected turns to perhaps claim itself as a murder mystery. Either way, if you’re prepared to persevere with it, the end is worth the wait.

Click here to watch the full series on BBC iPlayer.