The objective of the mission is to meet with blackmailers of Bernie. Bernie explains that the people that he and Niko are meeting are representatives of the blackmailers in Northwood. He says to take a "fast and intimidating car", there is usually a Turismo nearby. Bernie lets the reps know that he will not negotiate with them, and it is revealed that they are representing Dimitri Rascalov. The player is instructed to chase and kill them, but it is easier to focus on the road, and eventually they will reach a dead end in Castle Garden City. The player can then exit the vehicle and kill Dimitri's men with a weapon. Watch out for buses and trucks blocking your way.
In order to complete the mission the player must:
Take Bernie to the rendezvous to meet with the blackmailers
Eliminate the blackmailers
Go to Bernie
Take Bernie back to his apartment
The name of the mission is double entendre referring to three seemingly unrelated topics. On one hand, the name references the nature of the mission: To drive in order to secure a "union" between lovers; another is that Dimitri Rascalov blackmails Bryce to obtain control of worker's union contracts; and on the other, it references the names of highways where much of the car chase in the mission occurs, Union Drive East and Union Drive West.
The mission is one of only a handful of occasions in the game when a Super GT with a unique paintjob is available to be taken, as it is the Russians' getaway vehicle. After they eventually crash, the car can easily be taken.
Dimitri calls soon after this mission and tells Niko he will "cut him in" if he helps expose Dawkins, and also taunts Niko about being gay for hanging out with Bernie.
When the player gets to the Castle Tunnel a Police Cruiser will chase the hitmen, but will lose control and crash, prompting Niko to say something like "If half the cops in the city weren't on the take, I'd feel sorry for that guy".
Strangely, the police officer that chases the goons does not turn on his sirens. This could be either a mistake by the officer himself to represent the incompetent nature of the LCPD, or more likely a simple programming error.
When the Super GT hits traffic cars, they immediatley flip over, where as outside missions this would not be executed as quick.