“The Dissonant Interval: Part 1” is episode twenty-one of season four of Andromeda.
The Andromeda Ascendant rescues an unarmed ship that is being attacked by former Commonwealth fighters. The ship is bearing an ambassador from Arkology – a giant orbital station – to the Magog. The people of Arkology believe only in peace, and the ambassador says that he has successfully negotiated a treaty with the Magog. He also says that the Andromeda‘s crew’s impressions of the Magog are wrong, and that he will believe they are peaceful until proven otherwise.
At which, timely, point, Magog larvae erupt from the ambassador’s chest in a scene reminiscent of Alien. That pretty much proves the otherwise part.
The Andromeda heads to Arkology, but it doesn’t look like they will be able to move the construct in time, and the Magog worldship is coming. It doesn’t help that the inhabitants have decided that they don’t need to leave, but are they being manipulated by the Abyss?