"Vai Gorilla" is a somewhat different kind of Italian Poliziotesschi than usual, but a very good one and I even daresay a sadly underrated one. The protagonist for once isn't a tough and unorthodox copper, although has good connections with the local police commissioner, but a personal bodyguard - known on the streets as a "gorilla". Using a sneaky and old-fashioned trick, handsome young Marco Sartori (Fabio Testi) gets hired as the gorilla for a rich construction magnate Sampione (Renzo Palmer), but he rapidly finds out it's not a relaxing job. Sampione receives threatening phone calls from a criminal organization, led by a menacing creep with a German accent, who blackmail him into paying 600 million Lire (which was about 20$ in those days) or else they blow up stuff at his construction sites. When they also beat up Marco, and threaten to hurt Sampione's cute daughter - with whom Marco has a fling - our gorilla starts taking things personal.
The script is excellent, and expert director Tonino Valerii ("Day of Anger", "My Dear Killer") ensures a fast pacing, with a handful of really impressive sequences. There's a suspenseful sequence inside a ramshackle elevator, for instance, and particularly the climax is downright fantastic and hyper-violent. You haven't witnessed genuine Poliziotesschi thrills until you have seen this film's chase between a cop car and a passenger train. Fabio Testi is cool, but performances by both Al Lettieri and Antonio Marsina are even better.