Jordan and Cain figure out their professional dynamic; Drew and Paul must find a way to save a patient's severed hand; Annie shows up to the hospital with an unexpected guest from Scott's past; TC and Amira treat a Syrian child on the base.
When a major event cripples Las Vegas, Gil Grissom, Catherine Willows and Jim Brass return to help the team; D.B. and Sara consider the future; Lady Heather returns.
Peggy comes to a shocking realization but isn't aware her true enemies are closer than she thought; Sousa narrows in on the truth about Peggy.