At the exact moment that the Doctor shows up, a murder happens in one of the locations and, because of his timing, the Doctor and his companions are instantly seen as culprits...until the Doctor reveals his secret - he is actually the financial backer of the establishment and it would not be in his best interests to cause a murder there.
A mystery to solve and a love triangle to navigate as the three physicists, who built the technology the place is based on, work through their own complicated relationship. Throw a couple of powerful entities into the mix and you could have one helluva complicated and messy story or one helluvan adventure.
I'd actually say the book is both. At times it felt incredibly long. Like the story just wouldn't get to the point and then, suddenly, it would move on into another angle. I enjoyed the adventure, but it would have been nice if it had been a bit more formulaic. WOW, did I just say that? But it's true - in books like these, they are supposed to be almost like harlequin romances for geeks. Quick and semi-predictable with a few surprises. This one was like a feature length film. It covered a lot and the story roamed all over the place. BUT in the end - it wraps up nicely and the Doctor and sail off into the Time Vortex with his friends. Then again - I guess that kind of IS Doctor Who in a nutshell. I would call it a win.