Agree with all other experts - no consulting firms, including e.g. Big 4, will pay for overtime work. In fact, your hours are also not billable like they are at a law firm (where you literally charge every 15 minutes of time working to client). Rather, fees are agreed in advance so you basically bill clients by day, not by hour.
As I recall, the wording on my contract was: "the typical work week will consitute of 40 hours, Monday to Friday. However, based on business needs, you may, from time to time, be required to work additional hours". Hint: I have never worked a 40 hour week, so "from time to time" is just a formality.