Bihar’s story of shame, involving its policemen, is still unspooling but Kolkata today woke up to a nightmare when five policemen left for dead a colleague who tried to stop them from harassing a woman.An hour into the New Year, five men from the Kolkata Police reserve force, clad in mufti and packed in a taxi, followed a two-wheeler which had a woman riding pillion.Unable to stomach their obscene remarks and gestures, the woman’s companion stopped to confront them. No sooner had he done that, he was roughed up. This happened barely a kilometre from the Lalbazar police headquarters.Unknown to all, Sergeant Bapi Sen of the Traffic Police, also in plainclothes, was observing them from a car behind. He waded in to stop them from beating the man. The five, unaware of his identity, turned their ire on him, beating him mercilessly. The 36-year-old sergeant, who sustained head injuries when he fell on the tram tracks, is now battling for life at a private hospital.Confirming the incident, Soumen Mitra, DCP (Detective department), said two of the five policemen and the taxi-driver have been arrested. A search is on for the other three.Mitra said that Sen, a resident of Behala in south Kolkata, was rushed to hospital by friends but his condition worsened by the time he got there. His condition is critical, having gone into deep coma.