Teens in the Universe

The crewmembers of ZARYa starship supposed to mature during 27-year-long flight, appear at the Shedar system after less than one year of local time travel. Remote sensing verifies that one of the planets is very much Earth-like. Three of the crew members should land the new planet. They use the reconnaissance capsule and encounter the apparently abandoned planet. But the "extra" member of the crew Lobanov meets the strange more or less human-like creatures that escort him and his mates to the underground city. They become unreachable for radio communications.