What happens in Ludwig Series 1 Episode 5?

A headmaster is found dead in his locked study after a weekend at the school John and James once attended. Teacher Freya Chordwell discovers the body when the office is opened on Monday. A note and the apparent hanging suggest suicide, but its errors are implausible for a former English teacher and the post-mortem establishes strangulation. The sealed room becomes a murder problem with four prominent suspects: ambitious Freya, pupil Isaac, PE teacher Mr Bishop and John's elderly former mentor, Mr Todd.

The headmaster had reasons to quarrel with each of them. He was considering dismissing Mr Todd as his memory declined; Isaac faced discipline for smoking cannabis; and a letter on the computer concerned allegations about Mr Bishop's behaviour towards a pupil. Mr Bishop says he spent the weekend in Scotland and even proposed to Freya by video call from there. John dislikes him but cannot substitute suspicion for a way through the locked door.

Mr Todd gives John the conceptual turn. If leaving the room after the death is impossible, perhaps the killer did not leave then. John notices an apple core in the bin that has barely browned, unlike fruit discarded long before. Somebody ate it on Monday morning, after the headmaster was already dead and while the study was supposedly empty. Mr Bishop had remained hidden in the office throughout the weekend and slipped out behind the opened door amid the confusion when Freya and pupils arrived.

The video proposal supplies the supporting contradiction. School bells can be heard behind Mr Bishop, proving he was not in Scotland. He killed the headmaster to prevent action over the allegation and expected Freya, once promoted, to protect him; the proposal was also an attempt to secure that relationship after their argument. John gathers the suspects, explains why the killer never needed an impossible exit and names Bishop. When Bishop lunges, Mr Todd trips him, giving his former pupil one last practical rescue.

Away from school, Henry traces DI Matt Neville to a house in Wales registered in his wife's maiden name. Lucy drives there, with Henry secretly joining the trip, and finds the missing officer alive but frightened; Neville refuses to help and his wife urges Lucy to leave. Holly tells John that James kissed her at a Christmas party, apparently implying an affair, then phones Lucy late at night and insists on an immediate meeting about James. Mr Todd, meanwhile, recognises that John is not his brother. The episode ends with Lucy heading towards Holly and the family inquiry poised to collide with a death.

The emotional centre of the school case is John's fear of becoming isolated and forgetful like Mr Todd. Flashbacks show Todd protecting the young twins from bullies and teaching John how a good puzzle is constructed. His present confusion makes him look vulnerable and briefly makes dismissal a plausible motive, yet his single observation about the impossible exit unlocks the case. The banana peel John discards at home reminds him how quickly exposed fruit changes, enabling the comparison with the office apple. The solution honours Todd's teaching without pretending his decline is not real. It also lets Freya's discovery be reconsidered: opening the door did not reveal a room untouched since Friday, because Bishop was still inside it.

Who killed the headmaster?

Mr Bishop strangled the headmaster and stayed hidden inside the locked study over the weekend. He slipped out behind the door when the room was opened on Monday. John uses the fresh apple core to prove somebody had remained inside and the school bells on Bishop's proposal video to disprove his Scotland alibi.

Key clue: the barely browned apple core was eaten on Monday morning inside the supposedly empty locked room.

Red herring: the staged suicide and assumption that the killer had to escape after the death.