English teacher Dexter feels like he's being taunted by the universe. Everywhere he turns he's accosted by wedding invitations, housewarming parties and tables for two. Every last one of his friends is settling down with their other halves, while Dexter spends his evenings marking schoolbooks with his ginger cat for company. The thing is, he doesn't even mind being single; he just wishes his friends were too.

After another wedding ends in a drunken disaster, Dexter is musing on the situation and wondering what he's going to screw up next, when he gets the shocking reminder that he's not the centre of the universe. An alien spaceship has landed on the continent and when first contact is made, it's anything but friendly.

Humanity's numbers dwindle immediately, and the survivors are left to do exactly that - survive. Dexter gathers his friends and they all set off on a mission across the country, each with the goal of preserving their own lives in this new world. But these aliens are two-headed, tenacious and have technology beyond anything seen on Earth, so saving the day looks more and more unlikely as they track down Dexter's motley crew. In the end, perhaps it is the one thing Dexter dislikes most that will help him survive, if he can just stop thinking about himself for one minute.

Written to subvert any story that insists on including a romance subplot, as well as any science fiction story where untrained amateurs inexplicably have the right skills to save the day, The Third Wheel shines a light on those who are just trying to make it through to tomorrow in the face of overwhelming odds.