If you're a bookworm, chances are you've spent days or weeks falling in love with a novel, only to wind up wishing you could know what happens next. But what about wishing you could know what happened before?
It's an itch that novelist Irvine Welsh is about to scratch for his readers when he releases Skagboys this month, the prequel to the novel that made his name, 1993's Trainspotting. Fans will get to find out what happened to Renton, Spud and co to turn them into the heroin-ravaged anti-heroes they first met almost 20 years ago.
It goes us thinking about the other stories we'd love to see expanded, not forwards, but backwards - those novels and characters whose question marks seem to hang at the beginning.
So, from beloved children's classics to bleak dystopias, here's our list of the ten books we'd most like to read the prequel to.
Any prequels you'd like to read? Let us know in the comments below...