An airplane carrying 138 passengers returned to an eastern Indian city after a mobile phone text message from a passenger triggered a hijack scare, a news report said Monday. The message from a female passenger to a relative expressed fears about a possible hijack of the New Delhi-bound Indigo Airlines plane by a suspected terrorist on board, the Press Trust of India news agency said. The relative alerted air traffic control in Calcutta, which declared a security alert, it said. The plane returned to Calcutta's airport and was taken to an isolation bay and searched by security forces, who found no threat. Police detained the passenger who had sent the message for questioning, PTI said.