On arrival, the police examines the body and Chief Inspector Japp (a recurrent character is AC’s books) soon comes to the conclusion that Arlena was killed by a man. Strangling someone requires great forces and the marks left of her throat are the ones of big hands. On the murder scene, Lionel’s glasses are found.
There is a note of humour in that scene. As a matter of fact, Japp asks Poirot about his alibi, which is contrary to any standarts of the mystery novel: the detective never is suspect. Poirot looks insulted by the question. The same way, the standarts want that the murderer is never the maid, but someone from the same social rank as the victim.
The island is closed to visitors. Just t that moment, two bird watchers wanted to come to the island. They are not let in, but appear to be regular visitors. Major Barry once again, is observing them. Poirot notices something strange about the two men: they had no binoculars, which is something weird if they want to watch birds. They may have been lying about the reason of their visit.
During his interview, Kenneth Marshall says that murder is incredible, unbelievable, he is upset and says he’s chocked. There is no passion in his testimony though, he’s devoid of strong feelings, very rational, cool as a cucumber which is typical in the detective fiction. He describes his marriage as happy. He doesn’t have a specific opinion about Patrick Redfern, assuring hi relation ship with his wife was but gossip. He denies the fact that Arlena was having an affair. He says he was writing his letters until twelve, didn’t see his wife when he went to her room after breakfast, around ten. After typing his letters he played tennis. He recognises the glasses as Lionel’s. the fact he had separate rooms with his wife creates doubt about their happy marriage. In Arlena’s room, Poirot examines some perfume bottles because of the one that fell close to Emily Brewster. They also find a telegram, once more asking her for money.
Lionel says he ate breakfast, then went to the library on the mainland, to get a chemistry book and revise for his exams. When coming back he bumped into Miss Redfern and afterwards went swimming with her. He mentioned he swam till 11:45, he is sure of that because Christine asked for the time. He thought he’d be late for a radio broadcast he wanted to hear, but was surprised to arrive at the hotel at 12:10 only. He explains those spectacles are his old ones; that he keeps in case he’d loose his current ones, for emergencies. When asked about his feelings for his stepmother, he answers that she’s all right, which is obviously a lie, as she showed her hatred when arriving at the hotel. This brings suspicion. Poirot pays attention t check his strength when he shakes his hand to say goodbye (which he didn’t for the others), and has a close look at his watch in the process.
The maid confirms Mr. Mashall’s alibi, and when questioned by Poirot, mentions that there are a lot of bottles in Mr. Lane’s room. Mrs Redfern’s statement stallies Lionel’s. It sounds solid. She was indeed with Lionel and she confirms all information he gave. She was at the tennis court at twelve exactly. She says all that with a withdrawn attitude, a shy, small voice. She strengthens another hypothesis: She tells Poirot about the phone call she overheard, and adds more weight to the blackmailer theory that way. The blackmail story does make sense because Arlena recently inherited a fortune, and when Poirot asks Miss Marple to check arlena’s accountancy, we learn from her bank manager that she withdrew huge amounts of money from her account recently, up to, her entire fortune in fact.
From the interview of Miss Brewster, we learn Arlena was involved in her misforture a year ago. She had invested in a play, in which Arlena was starring, but her lead actress just walked out after the premiere. As a result, Emily lost her investement, she was annoyed, but it was in no way a reason for her to kill Arlena. She has an alibi anyway, and looks sincerely shocked. She noticed something unnatural about the way Arlena was lying, she looked like she was sunbathing, and her arms were in a weird position. She was pale below her tan. Japp interpretes: the paleness of death.
Poirot and the others are going to inspect the cave after this. Poirot notices a smell of perfume: Arlena’s. They also see footprints. Miss Darnley is the only one using the same perfume as Arlena, but she had an alibi. In the cave, Pirot, Hastings and Japp discover a lunch box containing some kind of drug. Japp’s hypothesis is that Arlena went into the cave, found the drug and was killed by a dealer who found that out, to silence her.
Knowing AC’s point of view of the outsider, it is unlikely that this will be the solution to the case, because the murderer is always part of the group the victim belongs to. Poirot thinks it is important to know why she entered the cave, before jumping to conclusions.
On further investigation, they find out that the book Lionel borrowed was entitled Dangerous Chemicals and Poisons. Maybe he was thinking of killing his step mother that way. Maybe he actually tried, failed and strangled her in anger. Lane also looks suspicious. During his interview, he has to explain his story too. He has gone to the mainland to visit friends. He came to the hotel because he needed a rest for his nerves. He probably had a nervous breakdown. He explains that his wife left him for another man, a member of his congregation. She was a wicked woman, and thinks she should be punished. His religious fanatic traits come back on his face, which makes him look suspicious again. In order to recover, his doctor made him take an opiate. An opiate is a drug derivated from opium. The diference between opium and an opiate is that an opiate is a legal medicine containing opium that a doctor can prescribe, whereas opium is an illegal drug.
Before that incident, Lane was vicar in Blackridge (Kent). This rings a bell in Pirot’s mind: the murder of Alice Corrigan. It took place in Blackridge, and was very similar, both in the way that the victim is killed, as for the husband’s iron clad alibi. Both cases are a snag: it seems impossible for the main suspect to have commited the crime.