This is the second of the final five episodes that David Tennant will be doing as The Doctor. The first was The Next Doctor that will air in the US soon, but Planet of the Dead ended up airing before. There will be an episode in November called The Waters of March and then the Christmas Special will be either be two one hour episodes on two nights or one two hour episode. Then it will be bye bye to David and hello to Matt.
This episode was a pretty interesting one as you have a jewel theif who is stealing a museum piece, played by Michelle Ryan(Bionic Woman), crosses paths with The Doctor on a bus that ends up crossing through a worm hole and lands them on a desert planet called San Helios. There they encounter a couple of different creatures to keep them challenged including the Tritovores, a fly-headed species and a stingray time creatures eating everything in it's path.
So they establish the worm hole is still open and try to figure a way to get back before they either get eaten alive or they let the creatures through to consume Earth.
There's lots of good little one liners and a good supporting cast along the way as well. This is a fun one to see and Michelle Ryan does a good job as the Doctors lates companion Lady Christina dw Souza.
All in all you will enjoy this one and it leave us down to David's last 3 hours as The Doctor and the transition to Matt. So enjoy it's worth the watch.