The police are concerned that Kingpin, aka Wilson Fisk, is going to get out of prison. The truck carrying the hard drives to lockup were hit and the evidence stolen. Lucky for Spider-Man, all evidence has a tracking tag applied to it, which he can track. After talking to the officer, the radar will appear on the player's screen.
At the location, Spider-Man will notice a truck containing the evidence. In order to retrieve it, he will need to defeat several thugs, most of which are on the ground. One is on an upper level. After taking the evidence, Spider-Man will need to return it to the precinct in Hell's Kitchen.
After returning to the original officer with the drives, Spider-Man's spider-sense alerts him to further danger. A nearby thug with a rocket launcher barely misses him and the officer. Take out the thug with the launcher, then head for the street in front of the precinct. The police will be under fire and there will be several thugs to defeat.
Several more of Fisk's men have made it to the rooftop are are beating up the original officer. Take them out and save the cop to complete the mission.