This was my first experience of Big Finish's Audio Novels - single narrated audiobooks of novel length (this one is 8 hours long).

This one was released for the 60th anniversary and was, apparently, the brainchild of Jon Culshaw who suggested the many (many) elements included - although writing it was given over to Lizzie Hopley.

The Third and Fourth Doctors, both travelling with Sarah Jane, become embroiled in Omega's latest attempt to escape his anti-matter universe. The story not only involves Omega and his Gell Guards but also [spoiler]two incarnations of the Master, Borusa, the Six, Sergeant Benton, Ogrons, Rocket Men and the Blinovitch Limitation Effect.[/spoiler] It was even going to feature Sutekh but that was vetoed (obviously because of what was heading towards our TV screens at that time).

Hopley goes for an epic, sprawling narrative to encompass all these elements with space stations, Earth deserts and distant planets with sentient, glass computers.

The plot follows a similar journey to many of the other Omega stories. Omega enlists the aid of someone in the matter universe - in this case, the Master - and uses them to help create his bridge across. This story, however, has Omega also pursuing the One who he believes is trapped in the Sandbox - a prison of many god-like entities created by the Time Lords and various allies.

What I liked about this is how, for a change, Omega isn't just a voice in the shadows. He feels much more present throughout and this is helped by Jon Culshaw's superb Stephen Thorne impression which really brings the villain to life.

Culshaw also does wonderful Pertwee and Baker voices so in many ways this almost feels like a full-cast story. Indeed, Culshaw's Delgado and Beevers/Pratt voices are also well performed.

I did struggle to follow the story at times. The changes of location became a bit dizzying as the story wore on, especially with two Doctors, two Sarah Janes and two Masters to keep track of, let alone the sundry other characters. The visuals of the Sandbox and its captives were interesting but I don't know that enough time was given to these god-like entities even though their names were extremely evocative and paint them with broad strokes at least - the Giggler, the Lone Horsemen and Mother Quiver.

The solution to defeating Omega, when it comes, is relatively obvious bearing in mind the elements involved but it is a satisfying tying up of the various elements.

I do think the story would work better with a few less elements (the Rocket Men and the Decayed Master are utterly superfluous and the Ogrons disappear after the first chapter or two) and the focus could be on the strange creatures released from the Sandbox, the Six and Omega's plan. Even the Delgado Master isn't really needed as he is just a conduit to Omega taking possession of a Time Lady which could easily have happened without him.

A little less planet hopping and a few less characters would have made this less epic but also maybe a little more easily followed as a story.

That said, this was an enjoyable listen and whilst it hasn't made me desperate to listen to more of the Audio Novels, it also hasn't dissuaded me. As an anniversary story it has a generous dollop of continuity and as an Omega story it builds quite nicely on The Three Doctors (the inclusion of the Gell Guards and their distinctive sound effects is a real highlight). Overall recommended - but be aware of the lengthy run time.