Heart of Tardis — Dave Stone

There's a serious reality breach in the 1950s American town of Lychburg, as the Second Doctor discovers when the TARDIS unexpectedly lands there, and he discovers it to be a city of anachronisms and temporal contradictions. Its people seem to be under the influence of a mysterious force...

What's more, the inept police force are baffled by a series of brutal and horrific murders taking place all over the city, with no witnesses. Meanwhile the Fourth Doctor is battling with the sinister Aleister Crowley, Head of the Provisionals, in 1980s London. Exactly what were the consequences of his disastrous post-war experiments in magic and the occult, and can the two Doctors save the people of Lychburg?