When American tourist Halley Hart accidentally drenches shy academic Henry Inglis in an Oxford coffee shop, it’s like he was struck by lightning. But after a series of chance encounters — and a fleeting kiss — Halley disappears in a taxi — forgetting to leave Henry her mobile number.

Although they spent just one day together, Henry can’t get this stunning PhD student out of his mind. He knows he has to find her again — but all he has to go on is her name, and the pair of sunglasses she dropped.

There’s only one thing for it. Henry must email every Halley Hart in the world until he finds his Halley.

They say you see Halley’s comet just once in your lifetime. Can lightning strike twice for Henry . . . ?