Jack-On-Top

Hunter and Wilson (Conrad Phillips), an MI5 officer, inform Callan and Meres that a highly trained unit of agents - all British - have been collecting information on security procedures for a foreign government.

The anonymous controller of this unit, nicknamed "Jack-On-Top", now possesses secrets that could set Britain’s security back five years. It is believed that this leader is to leave the country within the week, and there is only one lead: Jack Trochee, an Australian thief, now in a British prison.

Trochee has tried to bargain remission for information, pleading his innocence and claiming that he was tricked into working for the KGB. Whilst it is possible that Trochee does know who the controller is, rumour has it that Trochee was never paid, so may not shop his potential benefactor if he thinks he may still receive payment. Hunter decides that Trochee must learn that ‘Jack-On-Top’ is about to go behind the Iron Curtain, and sends Callan to interview the thief.

Following the interview, Hunter and Callan agree that they must now help Trochee to escape, to see where he leads them. Trochee escapes by scaling the prison’s inner wall, then climbing in the back of a bogus A.A. van. Callan arranges to meet Lonely opposite the house Trochee is staying in, and asks him to keep track of Trochee and find out who he contacts. Lonely agrees, and is provided with a car.

Meres is briefed on Stella Paxton (Daphne Slater), a teacher, who keeps micro-photography equipment at her home, and two associates of hers, Bradwell and Allen; the latter named by Trochee in his original exposé. Followed by Lonely, Trochee makes a phone call and tells the receiver he is not yet ready to make contact with Bradwell, and asks for his exit time to be brought forward.

Lonely then makes use of the phone box to report to Callan what he has heard, then follows Trochee to Stella Paxton’s flat. There, Trochee reveals to Stella that he is ‘Jack-On-Top’, and takes delivery of the micro-dots which have been prepared for him, plus the original photographs which the dots have been made from. Stella hides the dots in a sticking plaster which she sticks over a cut she makes on his arm, then provides him with a gun.

Trochee no longer has any use for Stella, and strangles her. He then makes a phone call, leaves the phone off the hook and exits round the back. His next stop is the home of James Holbrook (Richard Mathews) where he places the photos in a safe, while Holbrook is out. Holbrook is traced as the receiver of the phone call Trochee made from Stella’s flat, and when his place is searched the photos are found.

He protests his innocence, but when he learns that Trochee has betrayed the group and killed Stella, he agrees to talk, and informs Hunter that he received and passed on a message that the exit would be made between midnight and two, at the Sedgely Road swimming baths.

Trochee, standing by the baths, sees Callan and Meres arrive and makes a run for it. In the ensuing chase, he is shot, and falls in the water. Meres drags him out, and Callan pulls back the plaster from Trochee’s skin to reveal the micro-dots.