Will is a rich, child-free, irresponsible Londoner who, in search of available women, invents an imaginary son and starts attending single parent meetings. As a result of his liaisons, he meets Marcus, an odd 12-year-old with problems at school and a depressed mother at home. Gradually Will and Marcus become friends, as Will teaches Marcus how to be a cool kid, Marcus helps Will finally grow up, fall in love and possibly even commit to a real adult relationship with a lovely single mother.