You can find Jack Ryder inside the Interview Room at GCPD. During Chapter 9, he is following a lead to Lady Gotham (a small island on the west of GCPD) which might get him into trouble and it falls onto the Caped Crusader to look into the matter.
To start Lamb to the Slaughter Most Wanted Mission, head over to The Lady of Gotham and head to the south side or atop the statue. Once you arrive at the area, use the Disruptor to render the 2 Weapon Crates useless.
After destroying the Weapon Crates, fly to the cage where Jack Ryder is being confined in and confront the cult leader who calls upon his worshippers to save him. At this point, a 03:00 minute timer starts running and you must deal with 25 thugs along with Deacon Blackfire under this time limit or Ryder dies.
Keep your eye open for the blade attacks and brawlers from almost every side. Once the thugs have been taken care of, use the Remote Electrical Charge to shut down the 4 generators and grapple on front of the cage to apprehend Deacon Blackfire and drive him to GCPD headquarters.
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