The episode was entitled "Operation Cicero", and was adapted from the hit 1952 spy film "5 Fingers". It had one advantage over the original in that the main supporting role of Moisewitch, Cicero's contact man, was played by none other than Peter Lorre, who naturally walked away with the acting honors. But the episode was compromised by the fatal miscasting of Ricardo Montalban (of all people) in the role of Diello, the traitorous valet played so memorably in the film by James Mason. Montalban may be a great Khan in "Star Trek", but he is the last person one would ever imagine playing a dryly cynical spy who is willing to betray the Allied cause in WWII just for money and his own amusement. He brings almost none of the nuances that Mason brought to his portrayal.
The other actors in this episode are not miscast, but strictly unmemorable in comparison to those in "5 Fingers". The only other actor who can stand comparison with his movie counterpart is Alan Napier (Alfred the butler in TV's "Batman"), who plays Travers, the British intelligence agent played in "5 Fingers" by Michael Rennie.
There will be more episodes in this series, and they will certainly be of interest as early TV artifacts, but if you expect the same experience that you had in seeing the original films they are based on, you might be disappointed. The impression this series gives is similar to that of watching a touring company of a Broadway show when you have already seen the original Broadway production.