MI6 boss Michael Royston is asked over to MI5 when they became a aware of the arrest of a KGB treasurer. Victor Loshkevoi has been in the country since 1975 and the arrest was for handling stolen goods. Royston wants Sculby to infiltrate.
'C' has a report on Kyril and learns he wants to contact with Heather Stanton, who is a danger to Sculby's cover. The report also says there is a possible mole in MI5. Royston discovers the KGB want Loshkevoi knows he have to kill him.