Doctor Who Fights Masterplan “Q”

The Doctor and Jo arrive on the prehistoric jungle planet Quorus when they're suddenly attacked by a dinosaur-like animal. They notice a figure in the distance who they realise is the Master, who appears to be controling the animal with a gadget. He is then seen collecting something, making his way to his TARDIS and leaving. The Doctor and Jo follow him and track him back to Earth; however, they lose him when they enter the atmosphere.