I know it's stating the obvious, but you'll lose your completion bonus, in total, as well. You do not get anything for the time served if you don't complete the contract.
In the case of family emergencies etc, then I'm sure it'll come down to you, the agency and AJX to discuss it and agree mutual terms. They are not totally unfeeling robots (just robots
) and they have been flexible in the past for unavoidable situations such as you suggest. I feel confident they'd waive certain requirements if these things arose. Don't expect to keep the completion bonus though.