Female or Male 30 - 60

Faithful servant, but at the same time knows all “the dirty laundry” of his/her employers. Originally written as a male role, but could be played by a strong female. Although he/she has relatively few lines, he/she appears frequently, having to serve drinks, being sent to summon people or having to show people in. Tredwell assists Sir Claud in arranging his "scene" in the library. Tredwell locks the doors with all of the family and house guests inside so that Sir Claud could confront them and demand that one of them who stole his formula should return it. Likely it’s Tredwell who switches off the lights at the desired moment.

Female (25 - 30ish)

Richard’s half- English and half-Italian wife who was largely raised throughout the European continent. Stage directions describe her as a beautiful woman of about twenty-five. She is half Italian but speaks English perfectly. When Dr Carelli turns up unexpectedly at Abbot's Cleve and gets asked to stay as a house guest, she behaves erratically and Richard suspects that they might have something going on either currently or in the past because he sees him talking to her and suspects he even passed her a note. We know little about Lucia's past life in Italy. Sometimes she comes across as “nervy”. Eventually it is revealed that Lucia has a mysterious and dark past (which she is hiding) which opens her to blackmail and also makes her a suspect.

Female (50ish)

Claud’s dotty younger, maiden sister who never stops talking. Stage directions describe her as "an elderly lady of the old school, a little fussy but kind". Her niece says that she is too Victorian in her outlook and dress. She is very conservative, innocent, and prone to not quite getting the full picture of what goes on around her. She is a little fussy but kind in her intentions. She runs the household admin and prides herself on her organization and the quality of her coffee. Caroline worries about her niece Barbara, as she knows that the old-fashioned house is no place for a modern, young woman. However, she is equally disapproving of Barbara’s loud makeup and music. Initially shocked by her brother’s murder, she also finds the atmosphere afterwards rather exciting. Caroline floats around the house, often getting in the way and talking far too much. She has no idea that her words often reveal little nuggets of information for Hercule Poirot.

Male 30ish

He is the only son of Claud Amory. Newly married, he is very much in love with his wife Lucia who he married after a brief whirlwind courtship. He would do anything for her. He originally pursued a military career, but his father withdrew him from the army. Richard is intelligent, but he will never follow in his father’s illustrious footsteps. He’s not stupid, but he’s not the scientific genius that his father is. Richard feels like a prisoner in his home and is frequently irritable and gloomy. When he sees his wife’s reaction to Dr Carelli, Richard convinces himself that they are lovers and his feelings are thrown into disarray. He is shocked when his father is murdered and wonders if Lucia could be responsible as he knows that she is holding something back from him.

Female 20s

She is Claud’s niece and relies upon him for support as she is orphaned. Stage directions describe her as "an extremely modern young woman of twenty one". She is outspoken, lives rather on the wild side, and believes in speaking her mind, much to the horror of her Victorian aunt. In the course of the events, she takes a liking to Hastings. Poirot does what he can to pair them off. She wants a husband to take her away from her dreary life.

Female or Male (45 – 60)

Sir Claud’s faithful secretary. Originally a male role but could be played by a female . Observant and intelligent, and somewhat reserved. One of the few people who actually understands his scientific discoveries and is capable of organizing his notes. However, a misleading veneer….

Male (40s)

A mysterious visitor who claims to be an old friend of Lucia’s family. Equally charming and suspicious. Speaks with an Italian accent (not necessarily a good one). Becomes a threat. The character can be played as a real Italian or someone pretending to be a real Italian).

MALE 65 ISH

The patriarch and famous physicist. He is the irascible Lord of the manor, who has no affection for his relatives and is devoted solely to his scientific discoveries. Is killed off in Act One.

Male 30s ish

Famous detective from Belgium (slight accent) hired by Sir Claud to investigate a theft and death threats. Astute and insightful. Short, somewhat vain, with brilliantined hair and a waxed moustache, Poirot enjoys his creature comforts. Relying on his “little grey cells” to solve crimes, Poirot is notably meticulous in his personal habits and his professional methodology He has a great sense of dry humour and a sense of the ironic. Often only Hastings gets his jokes.

Male 40s plus

He is Poirot’s right-hand-man. Not quite as astute as Poirot, but by no means stupid. He often acts as Poirot’s sounding board, and evaluates theories and offers conjecture. He has a great sense of humour and is generally kind, affable and good-natured.

Male 40s

Sir Claud’s doctor, and an intelligent man who is not fooled by flattery or easily influenced. Very logical and capable of presenting the facts as he sees them.

Male 40s plus

Inspector Japp is decidedly working class. His accent is more rough, less polished. Think the servants of Downton Abbey or the Northerners of Game of Thrones. In charge of the local police. He and Poirot have worked a previous case. He respects Poirot and Hastings very much. Not what you would call a polished man, a bit rough around the edges prone to saying what he thinks too loudly rather than being diplomatic. Nonetheless, he is respected as an officer of the law by both Poirot and Hastings.

Small, minimal speaking role. Could double with Treadwell.