Victor and Hugo, Bunglers in Crime

Tinker, Tailor, Soldier, Dolt (2x11)

:

Victor and Hugo get their hands on the plans for a top-secret concrete-dissolving ray – just the thing for getting through the walls of, say, a bank. Did you notice? This episode's title apparently refers to the Alistair McLean novel Tinker, Tailer, Soldier, Spy.