There's something going bump on the Metropolitan line and Sergeant Jaget Kumar knows exactly who to call.It's PC Peter Grant's speciality . . .Only it's more than going 'bump'. Traumatised travellers have been reporting strange encounters on their morning commute, with strangely dressed people trying to deliver an urgent message. Stranger still, despite calling the police themselves, within a few minutes the commuters have already forgotten the encounter - making the follow up interviews rather ...