"Lie to Me" is the 585th episode of Casualty, and the 44th episode of the 21st series. It was preceded by "It Never Rains..." and followed by "The Fires Within". This episode was directed by Nigel Douglas and written by Stephen McAteer.
Cyd is left fighting for her life when she is bitten by a venomous snake. Dixie confesses a deep secret. Guppy's exhaustion leads to him making a reckless decision.