Old pals Dara, Robyn and Saoirse head to a small Donegal town for a school friend's wake, and to make sure a long-held secret stays buried.

Reeling from the crash, the gang vows to leave Greta and the past well alone, until mysterious red letters and an old notebook pull them right back in.

As a storm rages towards Knockdara, Saoirse, Dara and Robyn set up camp in the hotel, again. Liam probes deeper into another old friend of Greta's.

After some stellar sleuthing, the trio's search for answers takes them to a five-star resort in Portugal, where they're not the only ones on a mission.

Desperate to outrun Booker, the three friends scramble around St Patrick's Day Dublin. After Andrew's bombshell, Liam has a bone to pick with Saoirse.

Already in a tight spot, a confession ratchets up the tension between Robyn, Saoirse, and Dara. An exasperated Booker gets back on the box's trail.

Booker, Feeney and the Midwife receive a summons to Derry. At a Belfast police station, risky gambits, surprise reunions and smoke breaks transpire.

Having come this far, Saoirse, Dara and Robyn know there's no going back. Will they finally uncover the terrifying truth ... and manage to stay alive?