Owen: Tim Wylton

Sorrel: Janine Wood

In Columbia, Blenco, an English con man is about to be killed for stealing from a local gangster, Diaz. Blenco saves his life by promising Diaz that he will obtain a fortune in emeralds for him if he comes to England.

Jan is undergoing a management training and assessment course with other government agents at a country house. She performs poorly in the tests, and is told that her position is at risk unless she changes her independent attitude. A much younger woman on the course, Melissa, has huge theoretical knowledge, but very little practical experience. Jan is annoyed that her own vast experience seems to count for nothing against Melissa's book learning.

The Bugs Team are alerted to the arrival in this country of Blenco and Diaz. Ed and Beckett go to Diaz's office, but find little of interest save for the plan of an unusual building.

Ros realises that she knows Blenco's new wife, Sorrel. Sorrel had met Blenco in Colombia while working for an aid project. Ros and Alex go to a welcome-home party organised by Sorrel's father, Mandrake, at which Sorrel confides to Ros that she has made a dreadful mistake in marrying Blenco. Her point is underlined when Diaz appears at the party and, with Blenco, makes an attempt to kidnap Sorrel's father.

Beckett assumes the attack had something to do with Mandrake's previous secret communications work for the government; and Mandrake identifies the plans Ed found as being of an old Regional Seat of Government (or RSG), the nuclear bunkers built during the 1950s and 1960s, but since decommissioned. Beckett takes Mandrake to his flat for safety, while Ros accompanies Sorrel to her house. Diaz breaks in to Sorrel's house and uses threats against her life to once again get to her father. Diaz's men attack Mandrake at Beckett's, while Beckett is temporarily distracted by Christa. This time, Mandrake is abducted.

Beckett, Ed, and Alex uncover information about RSGs which leads them to deduce that Diaz and Blenco plan to use two old RSGs to access valuables.

Jan's exasperation with her course boils over, and she walks out - just as Diaz and Blenco arrive at the country house. Jan stays in concealment as the villains secure the building. Diaz's men go to the basement where they break through into a disused RSG. With threats against Ros and Sorrel - who are also brought here - they force Mandrake to rewire the controls of the RSG. With the RSG powered up, Diaz goes, leaving one of his henchmen behind to keep an eye on Blenco.

Jan meanwhile has met up with a frightened Melissa, who avoided being drugged along with all the other course participants. The two of them tackle one of Diaz's guards, and almost get into trouble - but are saved by the arrival of Beckett.

Ed and Alex go to the second old RSG site in the city, and find that the International Emerald Exchange vault has been built directly over it.

Once Mandrake has rewired the RSG, Blenco operates a remote transmitter located in the Emerald Exchange RSG. This high-powered transmitter causes the electronic security at the Emerald Exchange to malfunction. Diaz is able to walk into the Exchange and open the vault door.

Ros causes a setback for Diaz when she pulls the plug on the transmitter. The systems at the Emerald Exchange come back on line and Diaz is trapped in the vault area with a case full of emeralds - but security devices prevent Ed and Alex getting to him as well. Blenco operates a remote control device to reveal an escape route for Diaz. Ed and Alex pursue him through tunnels and finally catch him. Meanwhile, Diaz's henchman leaves Blenco (and Ros, Sorrel, and Mandrake) locked in the country house RSG with only a ticking bomb for company.

Beckett, Jan, and Melissa overpower the henchman, and get everyone to safety before the bomb explodes.

Beckett is invited to an evening-dress business dinner by Christa - who still believes that Beckett works for a firm of electricians. He goes, but lies to Ros about it. However, both Ros and Jan observe Beckett and Christa going off together.