The rain had turned Mumbai into a blur of headlights, umbrellas, and impatient horns.At 11:47 p.m., Arjun Mehta, a 32-year-old photographer, stood alone at Dadar station, staring at his phone.ONE NEW MESSAGE.«“If you want to know who killed your brother, take the 12:05 local. Come alone.”»Arjun stopped breathing.His elder brother, Rohan, had died three years earlier.The police had called it suicide.Arjun had never believed them.Before he could think, another message arrived.«“Coach 7. Seat 42. Don't trust the man with the red umbrella.”»Arjun looked around.Hundreds of people rushed through the station.And then he saw him.A tall man.Black shirt.Red umbrella.Standing completely still.Arjun's