Doctor Who and the Doomsday Weapon

The evil Master has stolen the Time Lord's file on the horrifying Doomsday Weapon, with which he will blast whole planets out of existence and make himself ruler of the Galaxy! The Time Lords direct Doctor Who and Jo Grant to a bleak planet in the year 2471, where they find colonists from Earth under threat from mysterious, savage, monster lizards with frightful claws! Hidden upon the planet is the Doomsday Weapon, for which the Master is intently searching.