In the fourth part of the alternate history series Red Moon, writer Robert Valentine allows the two protagonists – ex-MI5 agent Eddie Sloper (Bulcock) and scientist Dr Susan Madison (Holness-Dove) – to meet. Eddie has gone undercover to protect his life, and Dr Madison has problems of her own, and at first is not at all sure who if anyone she should trust. While happy to have Sloper’s help, Dr Madison recognises a shared need to uncover the truth. At the present, their paths seem to align, but their partnership is more serendipity than mutual regard.

Being hunted by a relentless assassin doesn’t help and Georgia Periam’s Mrs Jones is doing her best to get to Sloper and Madison before they achieve their own goal. This involves discovering exactly what is happening on the Moon, and (we hope) avoiding a devastating nuclear world war.

For the main it’s a two-handed, compact story, and although focussed on teaming up Sloper and Madison, and of necessity full of exposition as each tells the other some of what has occurred, it’s a tightly directed piece (writer Robert Valentine again), and Tshari King’s editing and sound design play a big part in adding to the atmosphere.

So far, the series has led with Sloper’s perspective and Dr Madison being mixed in here and there; in Eclipse, it’s Dr Madison who feels like the lead character, with Eddie injecting himself into her world. Whatever else the next episodes bring, listeners should not forget Sloper’s previous encounters with Russians, Americans and his former MI5 colleagues. This episode has a lull before storm feel, and there is a sense of a lot more intrigue to come.

RED MOON, PHASE 4: ECLIPSE / AUTHOR: ROBERT VALENTINE / STARRING: PHILIP, BULCOCK, YASMINE HOLNESS-DOVE, GEORGINA PERIAM, RICHARD REED / PUBLISHER: WIRELESS THEATRE COMPANY / RELEASE DATE: OUT NOW