Kolkata: A helmetless biker, Sumit Prasad (25), died and one of his pillion riders, Sailesh Giri (23), was severely injured after he lost control and the vehicle skidded on D L Khan Road near the entrance of Dhono Dhanyo Auditorium in Alipore around 3.20 am on Saturday.A second pillion rider, Mukesh Roy, was also injured. Cops said all three were from the same locality in Narendrapur and that none had their helmet on. Police took the three to SSKM Hospital, where Prasad was declared dead. Giri's condition was stated to be critical. An officer said, Roy was discharged from the hospital after treatment.