Onsite interview: 3 interviews.
Behavioral interview - 1 on 1 with a senior consultant or above; standard "why do you want to work here?" type questions
Behavioral/culture assessment during lunch - with the interviewing group plus some consultant through senior consultant level resources
Case interview - 1 on 1 with a senior consultant or above; standard case interview
The behavioral interview and the case interview can be switched, i.e. you can have the case interview first.