Playable

A veteran of the Balkan wars who arrives in Liberty City on his cousin's promise of a mansion and finds a cab office and a debt. He stays because the man who sold out his unit is somewhere in the city.
All 90 missions · 2 as giver
GTA IV
72of 90
Mission 72 of 90Story mission
Dimitri's men have been following Bernie, and Bernie's answer is to take a boat out past Firefly Island and let them come. The mission is a water chase that ends on land in Dukes when the survivors beach their boat and run.
The Infernus it hands over is the reason a lot of players remember it.
Bernie texts to meet at Pier 45, and the mission is only available between about a quarter to six in the morning and a quarter to seven in the evening.
The Russians are in a Squalo. They fire on the Tropic and then run rather than standing, so the middle of this is a pursuit down the water rather than an exchange.
They make land and continue on foot at a graveyard in Steinway. Beach the boat and follow them in rather than trying to finish it from the water, then go back to Bernie to close the mission.
Who this mission brings together, and the ground it covers.
Playable

A veteran of the Balkan wars who arrives in Liberty City on his cousin's promise of a mansion and finds a cab office and a debt. He stays because the man who sold out his unit is somewhere in the city.
All 90 missions · 2 as giver
Gives the job

A friend from Niko's old unit who reinvented himself entirely in Liberty City, and had nothing to do with the betrayal Niko came looking for.
5 of 90 missions · 3 as giver