Grace Vandenburg orders her world with numbers: how many bananas she buys, how many steps to the café, how many poppy seeds on her daily piece of orange cake.

She always sits at the first available table, starting from the top left-hand corner and proceeding around the room and inwards in a clockwise direction.

Every morning she brushes her hair 100 times, brushes her teeth with 160 strokes of her toothbrush. She can remember the day she started to count, how she used numbers to organise her adolescence, her career, even the men she went out with.

But something has gone wrong. Grace used to be a teacher, but now she is living on sickness benefits; as the parent of one of her students put it, ‘she’s mad’. Her father is dead, her mother a mystery to her, her sister sympathetic but not finally able to understand.

Only her niece Hilly can connect with her. And Grace can only connect with Nikola—Nikola Tesla, the turn-of-the-century inventor whose portrait sits on her bedside table and who rescues her in her dreams. Then one day all the tables at the café are full. As she hesitates in the doorway a stranger invites her to sit with him.