When you can play, walk out the door and hold auto-aim. Blast the nutter right beside you (The guy in the room to the left), then advance down the hall while blasting way at the next few guys. Heal after you kill then all, then make your way to the bridge, there's a guy waiting for you with a Shotgun. Cap him, then head down the stairs. My advice is to not pick up the Shotgun. There are 2 guys waiting for you here. Blast away at them with your dual Pistols, then turn right and go across the bridge and go down the hall. Heal if you need to. Make your way down this hall checkign every room as you go. If you get shot at too much, heal inside one of the patient rooms then head out and kill the rest of the wankers. When you've checked every room, head back towards the stairs, or go back upstairs and perform one last check of the floor. When you get to the stairs, turn right and go in the big room. A guy with an AK runs out of a room. Blow him away then go into the room he came out of on the right. Heal first if you need to. There's a fat guy with body armor in this room. He's the same guy from mission 19 and he takes a lot of bullets before he goes down - A full AK clip, and some Pistol bullets should do the job. Beware that whacking him does nothing at all. I've whacked him 20 or 30 times and nothing happens; he also gets to whack you and it inflicts a lot of damage. Run into the room with the AK you just picked up and shoot at the fat guy using short bursts so you don't run out of ammo too fast. After a bit, he turns towards the door and tries to get away. You'll probably use up all the AK ammo before he dies. Keep blasting him with your Pistols until he finally dies. Heal now, then head downstairs. If the cops tell you there are still more guys upstairs, then go up and check all the floors and rooms on each floor until the cops tell you otherwise. When all the bad guys are dead, go back downstairs and steal a car outside. When you get in a car, stop and wait. A cop from the hospital will follow you and come with you so you have some backup. From the direction that the car is facing, here are the directions to get to the next destination:

Turn around (180 degrees)

Turn right

Keep going down this road until you finally come to a 4 way intersection

Go through the intersection

The road isn't one way anymore

Turn left then right immediately after so you're going in the same general direction as the long road you were on

If your car gets busted, don't forget your cop passenger when stealing a new one, he'll come if you let him

Go through the intersection

Take the bend that goes left and take the immediate right

At the next intersection, turn right

Turn left at the main road and stay on the right side

When the road turns right, drive across the pavements and go down the street that goes down

Turn left then right

When you get to the bridge, take a right just after it

Turn right then right again and cross the bridge

Take the second left turn at the roundabout

Take the next left turn

When you get to an intersection, drive over the pavement to the right and take the road straight ahead

When you get to the end, turn left

Turn left again

Take the next left

Take another left at the small road

You'll see 2 Lexus' and a red Rover.

Get out of your car and start blasting away at anyone who comes out of the garage. Make your way to the garage with your cop passenger if he's still alive and with you. There are 2 guys in sight, cap them then advance until a 3rd shows his face. Blow him away then cap the fool in the hole under the car lift and another guy comes in the room. Kill him then heal before entering the next room. Your cop friend might still be outside shooting at a gang car way down the street if he hasn't already died yet. While you're healing, another guy might appear behind you. If so, cap him. As soon as you enter the room, blast the nutter by the Jeep. Go to the left side and kill the guy at the other end and then the guy who's hiding behind you. In the far right corner, blast the last guy. A few more might appear during the shootout. Go to the corner with the papers on the floor and the mission is complete.