Complete story — includes the ending
Sam moved out at Melinda's request, but he forgot something, so tries calling her to ask for it, but she won't answer his calls. Mel is scared by a break-in at her shop, especially when Dr Byrd's ghost shows up again. Eli goes to see the guy who broke in and discovers that he is another step-in (like what Jim did to Sam). Mel deduces that Dr Byrd is behind the step-ins, and works out that he wants another body for himself. Mel realises the other step-in is lost and confused somewhere in the tunnels and goes to find and help him, but the water valve has broken and the place is quickly filling with water. Byrd goes to get Eli and Sam is sceptical of his belief in a ghost he doesn't trust, but follows him down anyway. Since Eli can't swim, Sam goes to rescue Mel, and after his bag gets trapped on something, Jim's life flashes before his eyes.
Sources and content license
Source and revision history · Adapted from Wikipedia contributors, Ghost Whisperer season 4. HTML formatting and reference markers removed. · Content license