This is how you obtain the secret dossier in the secret tunnel between areas 14 and 17.

It is helpful if you have the vector cannon for this, but it isn't required.

Grapple and swing to the first platform, then use the vector cannon to hit the first switch above your head.
Then grapple the vent at the rightmost edge of the path and swing over the next sets of vents to the platform.
Switch to the bazooka and drop below and fire at the second switch.
Grapple and hang from the platform, drop off and swing up to the vents above.
Grapple to the vent above, swing to the next, then back and fire at the switch.
Grapple the vents and swing over the spikes into the section between.
You wont fall, there is a platform to catch you.
Ride the platform down and shoot the third switch at the bottom.
At the bottom of the platform path, duck and aim for the vents, pull yourself over. Grapple the vent above and wait for the platform to start heading back and swing onto it.
Duck immediately and shoot the last switch on the other side.
Grapple to the platform above and then to the next.
Pull yourself onto the vent and swing to the exit.
Drop below several times until you can see the moving platform below.
When it is about under you, drop down.
At the end of the path, walk off and grapple to the platform.
Here is your prize!