Bridge of Stone and Magic is partially a prequel to Bridge at War, set in Napoleonic times, when the original Lyndesfarne bridge was being constructed. It is also partially a sequel to Death on the New Bridge, set in the present time, with Kevin, Bret and Tanji investigating a suspected new crossing between the worlds, a crossing which was supposed to have been closed permanently several centuries ago.
Life for Kevin and Tanji had fallen into a regular pattern. Not a rut, exactly - the mysterious world of Lyndesfarne was even now far too new and exciting a place for Kevin to be in the slightest bit bored and, although Tanji knew vastly more about his own world than he knew about hers, there was still a great many interesting things for them to do together.
Kevin's introduction to Lyndesfarne - a series of events now quite a few years in the past - had been a slow and, he understood only in hindsight, extremely carefully managed process. Being initiated in the existence of what many might regard as an entirely mythical world was a delicate and protracted business, although the Other World itself was one whose description in myths and legends had a surprisingly consistent character across several continents and thousands of years.
His first exposure to the enchanting strangeness of the Other World was when Kevin had been commissioned as the leading architect for the construction of the New Bridge. This was introduced as a minor civil engineering problem: the design of a bridge between the mainland of North East England and the small island which lay a few hundred metres off the coast. For everything that he had understood hitherto, this was a distinctly backwater area and, even at the time, he wondered why such an elaborate and expensive construction was considered necessary.
It was not long before he had the first inkling of the truth: the stormy straights that lay between the Mainland of England and the island of Lyndesfarne was actually a crossing between his own world and another one; that the apparently deserted island at the far end of the bridge was a placeholder in his world's reality for the universe which contained the other. The same effect was observed from the Other World: his own world seemed to be represented by a tiny and uninhabited island.
The second surprise he had not fully appreciated until he had first visited the island, on the pretext of inspecting the Old Bridge - the original stone bridge built several hundred years ago. The engineering principles and technological solutions that Kevin had long ago studied, and more recently applied in the design of various sophisticated civil engineering structures were simply not applicable
in the Other World. Instead, an alternative set of rules and operating principles were in place, principles that even now Kevin found mostly incomprehensible and were generally referred to as "magic".
One principle which Kevin did understand was that magic was both pervasive and reliable: with the right gestures - mercifully, incantations did not seem to be necessary - anyone could activate everyday magic as easily as he could operate an electric light switch. While an individual's skills and innate abilities - coupled with extensive training - was certainly a factor in the invocation of more complex magic, Kevin found to his surprise and delight - and just a little pride, too - that even he had learned to fasten a cloak or turn on the illumination in a room without the slightest difficulty.
Magic seemed to be a property of the universe - indeed, Kevin was later to discover, both universes. There was nothing intrinsic in his world which prevented magic from functioning as intended. The reason magic did not, in general, work was that a carefully-designed barrier surrounded the crossing, fitting in the interstices of the passage between the Two Worlds. This interfered to prevent magical devices and artefacts from working when moved from Lyndesfarne. The same magical blockade also acted in the opposite direction, to prevent sophisticated technology from working in the Other World. The barrier was actively and carefully maintained, but occasionally something would slip through: some magical artefact would end up in our world still active - or at least partially so.
It was during the construction of the New Bridge that Kevin had first met Tanji. She was then a Guide in the Guild of Directions - the Lyndesfarne organisation that trained individuals to assist Visitors to the world of Lyndesfarne. Members of this Guild provided help with language and culture, and how to get about in a world where nothing worked as they would have expected.
Tanji was a petite and blonde-haired woman, although she was usually more blonde when on the Lyndesfarne side of the crossing. Kevin was convinced that people from the Other World were definitively as human as he was, but there was some common trait which gave them a certain elfin facial appearance. It was something about the shape of the eyes and the cast of the cheekbones, and a consistent tendency towards slightly pointed ears.