Killing Tomorrow (678-679). A fun sort of timey wimey problem, entirely focused on an inventor building a doorway into the future. Also cool for its focus on Horizon Labs [7/10]. 
 Morbid Curiosity (679.1). An even more in-depth look at Horizon and its members here, which makes it another winner. Though it's mostly a tease for the future, it's still pretty good for a .1 book [7/10]. 
 Space Station (680-681). This final story was the weakest of the batch. It was good action-adventure, but it wasn't much beyond that, and I think too much attention was spent on treading water before Ends of the Earth [6/10].