Neighbours returnee Steph Scully will snatch Lucas Fitzgerald and Vanessa Villante's baby son after ditching her medication.
The fan favourite, played by Carla Bonner, suffered a breakdown during her time in prison and now needs to take tablets daily to maintain a stable state of mind.
Fans will see that Steph hopes to reunite with Lucas (Scott Major) after arriving back in Erinsborough, so she causes trouble for his relationship by exposing the fact that Vanessa (Alin Sumarwata) was once married to another man and hasn't told him about it.
When the couple end up on the rocks as a result, things seem to be going as Steph had planned. However, that doesn't stop her from throwing away her pills after an argument with Toadfish Rebecchi (Ryan Moloney), who is concerned for her wellbeing after finding out about her recent breakdown.
Things later get worse when Lucas decides to give Vanessa another chance and agrees to cut all ties with Steph out of respect for his fiancée.
Realising that her schemes haven't worked, an increasingly erratic Steph takes the desperate measure of kidnapping baby Patrick, Australian magazine Soap World reports.
Patrick's disappearance stuns Lucas, but a conversation with Toadie about Steph's mental health issues soon leads him to realise who is responsible.
The kidnap plot will air as part of the dramatic eclipse episode of Neighbours, which will also feature Mark Brennan's return.