Despite some good acting and fine direction, The Poison Sky is unambitious for even an unambitious “Doctor Who” two-parter resolve. A lot of the plot hinges on teleportation and maybe teleportation really is just one sci-fi genre shortcut too many. “Who” can’t handle it.

And then this episode’s (relatively) out of nowhere cliffhanger is a great setup for the next episode, turning Sky into a strange bridging episode.

There’s a lot of weird drama and a lot of David Tennant not being right about things. He tries to convince military guy Rupert Holliday-Evans they can’t attack the invading aliens because they’re killing machines but the 21st century “Doctor Who” army guys do just fine. Then there’s a completely undramatic Kobayashi Maru, which maybe gets some okay acting from Catherine Tate and Freema Agyeman but it’s just forced melodrama. It doesn’t even give Tennant anything particularly good to do in that moment, instead relying on Ryan Sampson, who takes an interesting path to becoming a Tennant protege but apparently not companion material? Sampson was good last episode, bad this episode. All the other acting is about the same, including Bernard Cribbins getting tiring fast and Jacqueline King being bad.

Good direction from Douglas Mackinnon, good performances from Tate and Agyeman (who gets to play her third different person in three seasons on “Who”) while Tennant’s… eh. It’s not a good two-parter for anyone but it’s particularly not good one for Tennant, except when he’s seemingly messing with Agyeman’s character’s evil clone.

But those scenes never go anywhere, not really. Agyeman ends up with a surprisingly solid character arc on it though, which is a surprise because writer Helen Raynor initially seems to be using the clone as a device to avoid writing Agyeman’s regular character. Though maybe it’s just waiting out the runtime to avoid having to have any hard talks with Tennant; has there ever been any scholarly work on the psychology of the Doctor’s “friendships” with his companions and so on.

Good cliffhanger though. Very enthused for next episode. And Raynor does better with this two-parter than the last one. This one’s just a middling Earth two-parter, not a bad Earth two-parter.