"The Sandman" is one of my favourite Big Finish adventures. It operates on a vast, completely alien scale, making it both unstoppably ambitious and breathtakingly imaginative. The TARDIS arrival scene, in which the Doctor and Evelyn survey The Clutch, described as being like "a shoal of fish", thousands of shimmering ships moving together, some occasionally breaking away from the main fleet to pursue lone missions, gives it a scope above and beyond most of the rest of Doctor Who from the outset. This is a story brave enough to feature an almost entirely alien cast, with big names such as Anneke Wills and Ian Hogg cast as the reptilian Galayari, their voices modulated beyond recognition. Neither are the Galayari the only alien concept here - their whole culture is built up by the introduction of fascinating, unfamiliar concepts like the Sun Birds and the "Shushcoubre" - the Memory Egg. Yet the whole story is grounded in very familiar concepts - race memory, nightmares, the fear and anger Nrosha feels towards the Sandman for killing her children, and the figure that has stalked the Galayari for generations. The Sandman is the good old fashioned bogeyman in all but name, something for kids to be scared of in case he comes for them while they sleep - a point not lost on Big Finish, who cheekily implied (falsely) that he was something to do with the Zagreus story arc at the time, by mention of his name in "The Rapture" trailer.

This, finally, is the 'hook' - the fact that this mysterious monster, who appears to almost certainly be The Doctor himself - has been killing the young Galayari for hundreds of years and stealing their colourful skins for his coat. The story prevents us from really being able to question this for the whole of episode 1, thanks in part to the way the Doctor is forced to keep up the pretence (to Evelyn's uncertainty and disgust) in order to achieve his initial aims of stamping out arms trading amongst the Galayari, something he is bothered enough about to "pop back" every few years and keep a check on. Of course, when the explanation behind the eponymous creature comes it is both logical and clever - there are no cop-outs in "The Sandman", no cries that it was a Doctor acting out of sorts mid-"The Twin Dilemma" or even a doppelganger, which would have been the easy way out. Appropriately, it IS all the Doctors work, but as on several other occasions, his plans have been hijacked by another and he has inadvertently caused harm where he interfered to do good.

The story isn't an easy listen for the lazy - there is lots of discussion going on between people with modulated voices, indicating that it really wants to be a three hour feature film. Indeed, the cliffhangers are poor, Episode 1's being re-edited for Part 2 in grandest "Mark of the Rani" fashion to insert a get-out clause before the sound of the gunfire that prompted the previous episodes closing music kicks in. The others don't really warrant cliffhangers at all - but "The Sandman" doesn't seem to have been written for people that like everything traditional and easy to understand. It's vast in scope, and unafraid of telling its story in flashbacks. The alien creatures are as human in some ways as they are alien - and Robin Bowerman's Mr Mordecan provides an ally for the Doctor and Evelyn where usually you'd expect him to capture and lock up our two leads. Only Nintaru's race are badly handled, being too similar to the Galyari - the distinction between the two species is not made clear enough.

"The Sandman" is a lot of hard work, but ultimately it's an investment that pays off. The concepts on display here, the storytelling and the rewarding characterisation all deserves a lot more credit than they get.