The Linden and Lo Bianco characters are partners on the NYPD. On a call that turns out to be to an embassy, they get separated, and in the mêlée Lo Bianco's arm is injured so badly that he eventually loses it and has to go on disability. He's obsessed with finding out who did this to him, but the perpetrators have diplomatic immunity, so the NYPD won't pursue it. Lo Bianco (Mr. Outside) works on his own with unofficial help from his former partner Linden (Mr. Inside) who remains on the force. In addition to the main plot of finding the culprits, there is a lot of interesting dialogue and interplay between Linden and Lo Bianco. The plot summary says the bad guys are drug smugglers, but I distinctly remember they were smuggling diamonds not drugs.
It's standard fare for 70s cop movies, but I like it, so I gave it a 7.