Two rounds:
1st - phone interview with two senior leaders in the practice, high level interest, industry knowledge, career aspirations, etc. Interviewers were tough, but fair. They were friendly,but expected a level of professional polish and ability to think strategically. Definitely be prepared with why you want to work there and what you can bring to the table in terms of industry knowledge, thought leadership, or consulting acumen.
2nd round: In office: Interviewed with 4 people, 1 job manager, 2 principals, 1 partner. Two case interviews, two behavioral sessions.
Cases were actual cases from the interviewers' past clients. Be prepared for a wide gambit: One was a very formal case with numbers, slides, graphs, etc, beginning and end.
The 2nd case was much more conversational. I used a paper, but he wanted to make sure I could organize my thoughts and present the right buckets to investigate. Not sure if we even got to final numbers and an answer, much more about my thought process.