The most vacuous Doctor Who fiction is often that which relies upon juxtaposition of different eras. In his long overdue debut novel for the BBC, Dave Stone undercuts this by rendering the storylines allocated to the two Doctors present thematically evocative of their respective eras. Most specifically: if the second Doctor's era depicted order turned chaotic upon the pivotal arrival of the Doctor, in Heart of TARDIS his strand of the plot acts as a definition of his Doctor Who; the Doctor's experimentation results in an unexpected landing in an unconvincing American town - which might or might not be in America - and is the catalyst for all subsequent events and - in typically non-causal style - for some which have already happened.

Thus much of Heart of TARDIS appears to be thematically about perceptions of Doctor Who - a pernicious entity called Continuity, a race of hoarders with little understanding of either value or function. So far, so much a retread of Paul Magrs' recent Verdigris, you might conclude. But perhaps because Dave Stone's narrative style is unrelentingly - intentionally - showy and clever, the usual impression created by such an approach - of having stepped out of the story for smartass comments - is rather offset. So Heart of TARDIS is everything Verdigris thinks it is, with the added bonus of an astonishing density of ideas.

Stone does tend to amble away at tangents; environmental parameters are still being established well into the latter half, plot strands lie seemingly forgotten for several chapters before reappearing in unexpected places, or achieving resolution after only a few pages. For instance, the self-consciously pointless search for K9 which introduces the fourth Doctor and Romana to the narrative - we can but hope that one day all Doctor Who stories will begin with such panache - is rendered funnier by the complete absence of K9 from subsequent events.

Some aspects of the resolution seemed convoluted or even entirely absent on initial reading, but I'm prepared to believe that these - like the title - are merely beyond my comprehension. I'm sure it's all far more complicated than that.