"Mexican Stake-Out" is the worst episode of "The Untouchables" so far. While I am sure there are worse, this is the first big disappointment of season 1 and the other episodes were by and large extremely well made. The biggest problem about this one is that it simply makes little sense. And, with Martin Landau as the guest villain, it reminds me of a few episodes of "Mission: Impossible" in that the plan is ridiculously overly complicated and convoluted.
When the show begins, some weasel named Embry is supposed to testify against some mob boss named Newberry. However, the night before the trial, Embry is kidnapped from the Feds protecting him and most folks just assume he'd been murdered...but not Ness. Now here is where the story runs amok--Newberry wants his favorite henchmen (Landau) to pretend to help Ness and tells him that Embry is in Mexico. Now Ness, a Federal agent, has no authority in Mexico so he does what any intelligent lawman would do--he sneaks into the country with only one assistant (Vince Edwards). To make this brilliant plan even better, Ness doesn't know Spanish!! Duh. Yet, unbelievably, this ridiculous plan somehow is supposed to work and Newberry will be brought to justice!
Too many stupid story angles make this one a chore to watch. Even with a great character actor like Landau, it's just dumb.