it?â
She shrugged, conscious of a sinking feeling. âA walkway? Water mains?â
Noss laughed gleefully. âNo, thatâs what most people think, if they think about it at all. But itâs not that. Itâs a river.â
âA river?â
âYes, the River Westbourne. It runs out of the Serpentine and goes straight through here to meet the Thames at Chelsea. Of course, like the Fleet River, it runs mostly through the sewers now. But when they dug out the Underground, they had to provide a channel for it. So when you walk along this platform now, you can say youâve walked under a river.â
Mallard stared at Noss. Then he stared at Effie, rather more meaningfully.
âMr. Noss,â she said eventually, âyou have provided an answer that lives up to our expectations of you.â
âYes, itâs interesting, isnât it? A station managerâs life is full of tidbits like that. Do you know in 1940âa bit before my time, of courseâa bomb landed smack-bang on this station. Killed eighty people, but didnât make a dent in the river.â
âAh, Mr. Noss,â Effie sighed, âif only there were enough hours in the day, how I would love to wander through your extraordinary brain.â (âHaving removed it from your cranium first,â she added silently.)
Noss smirked and tugged at his sleeves. The action caused a cuff button to fly off and roll over the edge of the platform.
âOh, only too happy to be of service, Missâ¦â he prompted again. But Effie and Mallard had vanished.
âRivers!â exploded Mallard as they emerged into the bright sunshine of Sloane Square. It had taken a few minutes to squeeze through the crush of potential witnesses in the ticket hall. All the activity at the station had slowed the traffic around the Square to a crawl, and the noise of horns and gunned engines was deafening.
âSorry, Tim,â mumbled Effie contritely. By mutual consent, they used first names only when they were unaccompanied.
âI bet that self-important little git was responsible for that appalling color scheme.â
âHow about the card?â Effie asked, after they had moved through the concentric rings of police cars, cordons, and bystanders, who stared at them rudely.
âI donât know. Itâs certainly a puzzle, but Iâm not sure if thereâs any connection with Sir Harry Randomâs death. The symbol was entirely different, and I can make a case for Harry drawing his upon himself. In this instance, however, the murderer was clearly leaving some message. What did you make of those linesâa little like two lightning bolts?â
âCould it be a sales tag? Or a trademark?â
âWhat about those packs of cards that are used in telepathy experiments? Donât they have parallel lines?â
âI think those are wavy, not zigzag.â
Mallard stopped in front of the Royal Court Theatre, pretending to study the black and white photographs of the current production.
âI promised Iâd call Oliver,â he said, after a momentary fantasy in which his own monochrome image as a blood-soaked Banquo stared back at him from the display cases. âMaybe heâll have some ideas.â
Effie sniffed, and Mallard, watching her reflection in the glass, noted the passing expression with interest. Although Effie said nothing, she always had some physical reaction whenever Oliverâs name came up. Mallard assumed there was an element of jealousy, because he often discussed their cases with his nephew-by-marriage. The Yard frequently turned to civilian experts for technical advice, and when Mallard had no idea what sort of expertise was needed, he found Oliverâs vast store of useless information a useful starting point. But Effie, who had worked hard within the system to get where she was, clearly resented the treatment of the outsider Swithin as the