My sister and I have, without ever formally discussing the matter, fumbled our way into a Christmas present giving pattern of each buying the other the kind of book we would read that might - might - just exist on the edges of the kind of book they would read; the sliver of the Venn diagram that we have decided must exist. I genuinely enjoy the experience. This year’s entry into the canon was Dark Matter, more a thriller than last years cyber-mystery. A scientist is kidnapped by his other self from another multiverse instance, and he fights to return to his home universe. There is no great twist, no trying to guess what has happened or what the truth actually is, just the page-turning drive to find out what will happen next. It’s an effective thriller, with some rich (if occasionally underbaked) ideas around the multiverse, treading the fine line between the greater subtext of the piece and understanding that, really, that’s not the strength of the form. Sometimes it’s hard to find the door back to where you came, and sometimes it’s hard to know which door in the corridor it is you want to open. But you step through and find out, I suppose.