Two Parts - Technical and Behavioral. Often full day and called a "Power Day."
The technical interview is with one or more senior technology experts. Often the questions are very detailed relating to what the role requires. For example, if it's a Java role using Spring, you may get pointed questions about Inheritance vs. Composition and differences between Service, Component, and Repository. And if you don't get it right, you won't get a good score. This approach is great for hiring contractors who must deliver a specific skillset. But for perm employees, you want people who are malleable and can learn new tech quickly. In fact, that is what Capital One espouses - however, the interview process is very focused and narrow. Also, those without Computer Science degrees need not apply.
The behavioral interview weeds out people who "just won't fit in." It's highly subjective. You'll get questions like "think of a time you disagreed with your boss's decision. How did you feel? What did you do?" Capital one has a well-deserved reputation for inclusiveness - providing you're the right kind of person to be included. While you might find a diversity of races and nationalities, the company is very conservative (in every sense). Liberal or innovative thinking is not welcome. Introverts are not welcome. They crave type-A personalities who are bombastic and driven. The quiet, contemplative loner will not be selected - and if selected will not survive long.
While they stress innovation, truly innovative ideas are quashed quickly. So, if you have a radical idea (say, like avoiding Test-Driven-Development or Unit Testing in favor of only Behavior Driven Development) you will likely not get a good score. In almost every case (both Technical and Behavioral interviews) the conventional wisdom prevails.
Once you are interviewed, (three interviewers for each of the Technical and Behavioral) the interviewers will meet and compare notes. They will make sure your stories match. They will rate you as "Recommend," "Unsure," or "Do not recommend." If "Unsure" they will be challenged to defend their position. The hiring manager has the final say - but they will likely take the opinion of the interviewers.