James Cagney gives his final lead performance in this film as he retired from acting due to his bad experiences while making this film and he did not come back to film until 20 years later for his supporting role in Ragtime. Although Cagney evidently did not have not have a very good time making the film, apparently especially due to the behavior of chronic over actor Horst Buchholz, that really can't be noticed in Cagney's performance. The part of C.R. MacNamara is one of the prototypical screwball comedy lead which tends to be a business man of some sort who has to orchestra some crazy scheme while craziness occurs all around him because of this plan. That is certainly the case with MacNamara who has to deal with his bosses flighty daughter, her sudden communist husband, the Russians, his oddball German staff, and his own family.
This may be an aging Cagney technically speaking but he has much energy that he had back when he was doing Yankee Doodle Dandy. Cagney really is one of the perfect actors for a screwball comedy as he just is always on in his scenes. The film never stops in its comic absurdity and neither does Cagney. There is plenty of dialogue for Cagney to get through the film and Cagney is a master of it. He does lose a single beat as he develops the right rhythm for the dialogue. It is not stop and Cagney is more than up to the task to keep it going with that constant fluidity needed for this kind of film. A good screwball comedy really needs to never stop its motions and Cagney makes more than sure of that. Cagney knows exactly how to deliver every line with expert timing and precision really getting the most possible out of the comedic potential in the script.
Cagney is always a physical performer as he rarely ever seems restrained in his movements. There is of course all his dancing in Yankee Doodle Dandy, but even when he's a gangster there is certain something extra he brings to the way he beats someone or even the way he shoots his gun. Technically here Cagney is just playing a relatively normal guy who technically does not have to do too many physical actions throughout the course of the film. That does not matter though because Cagney still has this way of accentuating every gesture even the way he walks has something very special to it. This absolutely works brilliantly for the part and the film itself as it makes it as though MacNamara is moving just as quickly as everything that is going around him. Cagney in doing so makes sure that he is never overshadowed by anyone or anything in the film leading it all the way through.
This technically speaking is probably not the deepest character he ever played as MacNamara's objectives are clear from the beginning, and even his problems with his wife over his affairs with his secretaries is basically just played for laughs. That is not a problem though as Cagney's whole performance is played for laughs and Cagney certainly derives plenty of those out of the material. He acts like a torpedo and delivers the screwball comedy right through its course and doing his best to avoid any faults. Cagney almost makes Buchholz tolerable because just how much he runs circles around him in every scene they share together so he at least makes the scenes still enjoyable. Cagney here pretty much utilizes almost everything that makes him stand out so well as a performer and that works incredibly well into making this one very entertaining performance to watch.