From publisher blurb:
The Doctor needs YOU to save the galaxy from the bizarre manipulations of a madman in Crisis in Space.
The Doctor's assistant, Turlough, intercepts a message from Outer Space. Garth Hadeez, the Overlord of the gruesome Golons, has instructed his slaves, the midnight-black Neroids, to release a new planet into the Solar System.
But the planet is a fake. Designed to resemble Phobos, one of Mars's tiny twin satellites, it is actually a Black Hole capable of annihilating the entire Solar System.