WARNING: DO NOT READ IF YOU HAVEN’T SEEN THE END OF SEASON THREE!

Supernatural writer Sera Gamble has dropped hints about future plotlines for the series' fourth season in an interview with Digital Spy.

The shot of Dean in Hell that closed season three may not be all that it seems."I like to think of Dean as sitting in the chair in the waiting room to Hell. It's not even what he's going to experience once he gets into the first chamber of Hell... There's much, much worse to come for him!" Gamble told Digital Spy.

Gamble also indicated that the production team would like to bring Jeffrey Dean Morgan back as John Winchester, although "I don't think anyone should hold their breath because he's in the midst of a huge movie right now."

The writer also promised that some season three plotlines that were sidelined as a result of the curtailed season will be revisited including "why Sam and Dean's mom's friends all got killed".

Supernatural season four begins in America in September and in the UK next January.