This mission comes after the League of Shadows have made their move — Gotham is under attack from the league’s assassins, and your friends are one of their targets. You’ll need to protect the contacts you’ve made in order to use them again (and to proceed with the main story).
When this mission begins, you can immediately leave the Belfry. Once on patrol, tap/ to open the Activity view. Here, you’ll be able to access the 7.1 cae file challenges — select “Help Lucius Fox”, and then hit the Track button to get yourself some GPS guidance.
Make your way to Lucius Fox’s location, where he’s rather comically cowering in a bubble shield while the League’s assassin’s try to hack their way into it. You’ll need to keep the assassin’s off of the hacking stations while fighting them — there are two hacking stations (see below), so make sure you’re constantly checking both of them. You can also try to utilize the numerous explosive containers in the area to deal some good damage to the enemies; try to lead them towards one and then hold /to aim, then press /to shoot at the barrels.
You can also earn some bonus rewards here by doing “Perfect Attacks”. To do a Perfect Attack, you have to Perfect Evade (dodge right when the enemy’s attack indicator gets the jagged edges on it), and then tap the melee attack button right afterwards.
Once you’ve defeated all the enemies, Lucius will come out of his bubble, and you’ll need to talk to him. After the cutscene, open up the Activity view again (tap/ ), start tracking “Help Detective Montoya”, and follow your GPS/the HUD icon to her location. Once there, you’ll need to defend the four cops from the League of Shadows assassins. This fight is a little easier than the last one, since instead of one guy hiding in a bubble, the people you’re protecting actually fight back.
The bonus rewards are a little more of a pain this time, however — you need to defeat 2 enemies with Ranged Attacks, and perform 3 Perfect Evades. While fighting, make sure you keep an eye on the Officers’ health; if they’re getting low, try to find them and draw the attention of the enemies attacking them — you can heal, they can’t!
After defeating all of the enemies here, you’ll be called back to the Belfry (I guess Dr. Thompkins isn’t really in danger, although you will need to rescue her before you can use her as a Contact again). Once the cutscene at the Belfry ends, you’ll earn your mission rewards.