There are home invaders in the house. If you call the police, they might hear your voice. Or worse, they're in the same room you're in. How can you get help?
One way is to call emergency services on your cell phone but keep it on mute and say nothing. The police will hear the home invaders and send a squad car down.
This is the Covert Emergency Call. When someone finds a way to secretly call for help despite the danger being right there in the area. It doesn't have to involve the phone, but could involve the internet, Morse code, saying something that tips off would-be rescuers while sounding innocuous to the captors, or any other means available. What makes the trope what it is, is that the emergency call for help was unplanned, and is somehow kept hidden from the captors.
Related to, but not the same as, Covert Distress Code, which refers to a pre-determined code meant to tip people off. This trope is more about improvising on the spot.
- In Fantastic Four #348, Mr Fantastic is secretly being held prisoner by a Skrull inflitrator disguised as Sue. As the leave the Baxter Building together, Reed tells his robotic assistant that he and his wife are going on a day trip and that she should tell that to his "friends in the Marines". The robot, knowing that Reed has no friends that are in the Marines, looks up the phrase, discovering its history as a Covert Distress Code and realises that Reed is in trouble.
- Skeets, Booster Gold's personal assistant, comes with a "silent scream" that can alert his master of anything attacking him. The Linear Man in the Superman story arc Time And Time Again uses that to his advantage to lure Booster Gold to Metropolis so that he could capture him.
- One of agent John Kruger's last acts before losing consciousness is to text the "bug out" code to key witness Lee Cullen in Eraser. Kruger's boss Robert Deguerin drugged Kruger with the intent of extracting the whereabouts of Cullen because Deguerin is a double agent, working with the villains to silence Cullen before she can testify.
- Cellular is entirely about this. A kidnap victim manages to repair a broken phone and uses it to try to reach the police without her captors knowing.
- The Multitasked Conversation in In the Line of Fire involves Horrigan secretly communicating to police snipers where they should shoot.
- In Air Force One, the President is already in the process of calling the White House when he is captured. With the phone in his pocket, he tells his captor that the plane would automatically dodge any incoming missiles - which the Vice President correctly identifies as "an order from your Commander-in-Chief" to fire at the plane.
- Convicted embezzler Miles Eastin becomes a covert agent for the bank he defrauded in Arthur Hailey's The Moneychangers. Eastin infiltrates an organized credit card scamming operation, and alerts his superiors by using a credit card with the name H E Lincolp (HELp).
- In the episode "Cops and Robbers", Castle happens to be talking to Beckett on his cell phone as a bank robbery begins. He keeps it hidden long enough to alert the police, but is soon found out.
- In another episode, Ryan is working undercover as an Irish mobster when he is discovered and taken to a remote location to be murdered. He manages to dial his partner's number on one of his captors' cell phone and describe where he is being taken so that the cops are able to rescue him and capture the mobsters.
- Cade in Modern Day Treasure Seekers decides before walking into a Hostage for MacGuffin situation to call 911 (emergency services in the US) and stick the phone in his pocket to allow the police to hear the conversation, ultimately preventing him from being kidnapped as well.
- In real life, emergency services are starting to enable texting to them; this is one of the reasons for doing so, along with hearing-impaired access.
- Jeremiah Denton, an American POW captured in Vietnam and forced to make a video claiming the prisoners were being treated well, secretly blinked the word "torture" in Morse code to communicate that the words coming out of his mouth were a lie and get the word out of what was really going on.
- In 2015 a woman being held hostage by her abusive boyfriend persuaded him to let her order pizza using an online app. She wrote "911 Hostage" in the "comments" section of the order, and the pizza restaurant sent the police to her house to investigate.