Metronome, by Tom Watson

Second paragraph of third chapter:

‘Lionel, you mean?’

Two people on an isolated island, exiled with each other for the crime of conceiving a child without a permit; and then their world changes. The build-up of tension just from the routine of isolation is well done; and the shift of perspective as the outside world reasserts itself is really superb. Not a comfortable read, nor a quick one, but very nicely executed. Recommended, like the other Clarke finalists. You can get it here.