An Eternal Circle

Iceland, 2010, and the ash-cloud generated by the eruption of Eyjafjallajokull volcano brings air travel across much of northern and western Europe to a sudden and decisive halt.
Worse still, scientists predict the volcanos neighbour, Katla, will almost certainly erupt within months in accordance with historical records, an established geological pattern and deep subterranean connection between the two locations but after more than a year of tense, critical monitoring, there are no outward signs of the mountain coming to life again.
Compared to Eyjafjallajokull, Katlas eruptions are known to be particularly violent, generally rating 6 out of 8 on the universal volcanic explosivity index (VEI).
As 2012 draws to a close, much of Europe is gripped by another icy winter while the UK basks in unseasonably-warm air drawn up from the Azores. With barely a week before Christmas, Werner and Sophie embark upon a short fact-finding mission to the Hannover area of Germany but this seemingly-innocuous decision not only breaks the long-standing tradition of celebrating Tyras birthday and observing a time-honoured religious festival from both their pasts, it also sets in motion a bizarre sequence of events which, ultimately, causes Tyra to question her very sanity.
Ominously after years of apparent dormancy and quiescence, Katla begins to exhibit signs of reawakening but a culmination of weather phenomena including a severe Atlantic storm and unusually-vigorous pressure systems over the continent and parts of Scandinavia ensures the eruption will have dire consequences for more than just the aviation industry.