Fear Itself (8th Doctor)

In the 22nd Century, a few short years of interstellar contact have taught Man a hard lesson: there are powerful, unstoppable, alien forces abroad that are nightmare manifest. It's a realization that deals a body blow to Man's belief in his own superiority and leaves him with the only option he has ever had: to fight. When the Doctor and his friends are caught in the crossfire, they find suspicion and paranoia running rampant, with enemies to be seen in every shadow. The fight against alien forces is no job for an amateur, and for a Doctor only just finding his way in the universe again, one misstep could be fatal.