Desperate to find a missing boy and his killer father, DCI Mathias breaks protocol and sets off into the mountains alone. With the clock ticking, Mathias puts his life on the line.

As Mathias and Mared investigate Catrin's death, they begin to suspect it might be linked to the death of former police officer Iwan Thomas. However, independent investigator John Powell is on the cusp of ruling Iwan's death as a suicide - could this change things?