What do an astronaut, an off-duty cop, a scientist and two backpackers have in common?
It’s an alien threat that the Doctor hopes to stop.
This week’s episode has a comment about pollution but it’s not as preachy. It also mentions that everyone is connected, and does that fairly well. It’s also a bit topical because of the recent headlines about the coronavirus.

SPOILERS BELOW

It starts with British astronaut Adam Lang (Matthew McNulty) experiencing problems with his ship getting back to Earth somewhere over the Indian Ocean. Meanwhile, a guy named Jake (Warren Brown) gets a bit too aggressive catching a shoplifter. It’s later revealed he’s a cop on a sabbatical who’s having some problems.
In Peru, two vlogging backpackers named Jamilla and Gabriela (Joana Borja) wander around Peru and find a field with a lot of litter. They also find a lot of birds acting very strangely. Later, Gabriela can’t find Jamilla, but meets someone else….Ryan.
Seems the Doctor is already on the case. She is in Madagascar, where a man has washed up on the beach. He was in an American sub in the Indian Ocean, when it hit something. He’s also infected with an alien disease that literally disintegrates him. It’s no coronavirus. It’s worse.

Jake soon gets a text to come to Hong Kong…and it’s from Adam. Jake also meets Graham and Yaz, who’s been sent by the Doctor to investigate strange energy emissions. They find the source, namely aliens like the one above…and Adam, too. This might be an experiment, and maybe connected to what happened to the American. It’s also revealed Adam knows Jake…as his husband. More on that later.

Back in Peru, Gabriela finds Jamilla (Gabriela Toloi) at a nearby hospital, but she’s been infected. The Doctor arrives, but too late to save her. They take back a bird that was infected with the disease, and examine it at a lab in Madagascar that’s run by a scientist named Suki (Molly Harris). They’re able to learn the disease targets plastics, even microscopic pieces, and absorbs anything. It’s not long before Madagascar also has a massive (for lack of a better term) birdemic. They’re the same flock as the infected birds in Peru.

Soon everyone is in Hong Kong and find Adam. However, Yaz wonders about a machine the aliens wanted, and wants to stay and get it back. Gabriela also decides to stay behind. Meanwhile, Jake admits they are separated because he couldn’t bear to lose Adam while he spends months at a space station. He admits it’s been tough, and his heart-to-heart with Graham is a nice scene.

Jake’s concern for Adam is also done very well, especially when it’s revealed Adam has the disease, too. Seeing two men express romantic love, even as a married couple, isn’t seen too often on TV, but this episode pulls it off very well.

Yaz and Gabriela eventually find out one of the aliens in Hong Kong transported somewhere, and they follow it. They think they’re in another planet, but they’re actually under the Indian Ocean. They even find a piece of the missing sub, and a spaceship.
They also find out Suki’s an alien. She says the disease is called Praxeus, and has killed much of her planet. She and some other aliens went to Earth to use it as a “petri dish” to find a cure. They crashed, and it set off a series of events where a massive ocean of plastic pollution gathered, and the disease absorbed it. The birds eat the plastic, and could spread Praxeus everywhere.
However, the Doctor finds a cure, and Adam insists he tests it out. She tries to convince Suki to help them find a cure for her people, too, but she eventually dies, too. The cure does save Adam, though.
The Doctor uses Suki’s ship to spread the cure for humans, and sets the autopilot. However, it doesn’t work.
Jake decides to be the hero and fly the ship himself. He succeeds in spreading the cure, but the ship is about to break apart. Fortunately, the Doctor pulls him out just in time. It’s a corny happy ending, but a good one.

The Earth is safe, and Gabriela has two new traveling companions. Hopefully Adam’s bosses also know he’s OK.

The episode argues that we are all connected in one way or another, and throws in a comment about pollution that was more subtle than the “orphan world” episode. Adding the story about a troubled same-sex marriage was a nice touch, too. Best yet, the Doctor and her Companions all had a chance to shine.
As for what happened last week, it’s bound to come up again. Still, there’s only four episodes left this season. Next week, the crew starts seeing things in different eras and places.