Slater misses Gemma and she kills him with a burst of automatic fire. Outside, the soldiers fear the worst and rush in to help, only to find Gemma standing over the body looking pleased with herself. They search the house and find the transmitter. Sarah says that if the Cretaceans attack, the transmitter can be used to lure them away from the town. Gemma and Captain Hunt relish the thought of trapping the monsters and blowing them up, but Sarah says there might be another way. Captain Hunt says that he needs time to set up an ambush anyway.
From now on, very little happens, even by the standards of a typical episode 3. Every so often, the camera sweeps over the sea accompanied by portentous music, but this never leads to anything. Sarah and Gemma hang around the harbour having a vague and inconclusive debate about the morality of killing the Cretaceans. Soldiers aimlessly drive around in a Land Rover. Old Evans continues to be a “funny” Welshman.
At about 20 minutes, Sarah announces that she must swim alone to the Cretaceans’ undersea base to negotiate with them. Gemma is distraught, saying “no, they’ll kill you”, but Sarah dives into the harbour and swims away. After swimming for what seems like several miles, she is suddenly attacked by an octopus.
After a very long recap, Sarah escapes from the octopus. She spends a long time debating with the Cretaceans in their secret undersea base (which resembles the floor of Ealing Studios with some black drapes in the background). She seems to have made a deal with them and goes back to confirm with the humans, which involves another long swim. After Sarah leaves, the Cretacean leader is deposed and killed, and the new leader orders an attack.
Sarah meets Captain Hunt and tells him about the truce. He is disappointed but agrees. Sarah goes back into the sea to meet the Cretaceans but it’s a trap. She uses her psychic powers to blow up a Cretacean and escapes. As she swims back to shore, she sends a mind message to warn Gemma that the Cretaceans are coming and to divert them away from town.
Gemma and the soldiers get the transmitter and race away in the Land Rover. When they arrive at a nudist beach near Swalecliff, they hurriedly set up defences and start the transmitter.
The camera lingers on the waves, filling in time, I mean building tension. Six Cretaceans come out of the water. Then another six in a slightly different place. Then another six, and so on. There is a surprisingly spectacular battle full of machine-gun fire and explosions. It goes on for a long time and becomes less spectacular. At the water’s edge, Sarah confronts the Cretacean leader. They wrestle (yes, it did look ridiculous).
As the Cretaceans are wiped out and the gunfire dies down, Gemma rushes forward and finds Sarah lying on the beach. Gemma is shocked, but discovers that Sarah is still alive. Gemma calls for help, and some soldiers carry Sarah away on a stretcher. This is the last we see of them until 1986, but there are still a few minutes to fill, so there are lingering shots of life going on at the harbour. The story ends with seagulls circling overhead, and a typically incomprehensible epilogue to Sarah’s voiceover.
The octopus prop was previously used by Marty Feldman.