Martha and the Tenth Doctor have been on holiday to the resort planet of Nacre – but now it’s back to work, and they have a mystery to solve. The TARDIS has brought them to a space station in 2088, and there they meet Professor Morris and learn about the mysterious Benefactors. Planet Earth is dying due to pollution and global warming, and the Benefactors promise to be the salvation of mankind. But are they too good to be true?