New theory
Jacks there to operate on a mystery person thats of great importance to the others.
Sawyers there because hes going to be the organ/tissue/blood doner for the operation.
(rare blood type scenario)
Kates there as insurance that the job gets done.
The others know that both men, have feelings for her, and she will be threatened with harm unless both men co-operate with whats needed to be done.
I WOULD LOVE TO TELL YOU, TOLD YOU SO ON THIS! wait and see 