Continuing after the cliffhanger last week, this new episode is really very exciting. An action premise as the Sontarans attack UNIT, in an attempt to take over earth to use for their cloning process.
Donna once again doesn't disappoint, her acerbic personality zings even when she's left alone. And Martha's doppelganger is excellently played, distinguishing her from the Martha we know. There's a nice meeting of the two versions that's perhaps slightly soppy, but well done anyway.
The visual effects this week are phenomenally good. Explosions and fire and spacecraft and laser bolts. Wonderful stuff.
And of course: Click for spoilers
Next week's episode looks to have a very controversial element. Click for spoilers
But who knows? We shall see next week what it really refers to.