Brace yourselves, Avengers fans who still haven’t seen Infinity War, as I’m about to spoil some of it for you.

There is a way to find out for yourself what the most heart-breaking scene of the movie is, and decide whether the ending is breaking any hearts — watch Avengers: Infinity War. You can also keep reading this article, where I’m going to talk about it in detail. This is your last chance to avoid some major spoilers.

Let’s start with the ending, where so many Avengers die with a snap of Thanos’s fingers inside that powerful gauntlet. It’s all extremely shocking to the viewer, but the shock lasts only for a few seconds. As soon as you realize that characters that have to appear in future Marvel movies are turned to dust, it becomes clear this is just a cheap cliffhanger trick. It’s a Game of Thrones Jon Snow kind of ending, one that feels even cheaper than that, because we know for sure characters like most of the Guardians, Spider-Man, and Black Panther can’t disappear from the Marvel universe that easily.

Most of them will be revived in Part 2, there’s no question about that. But there are plenty of genuinely heart-breaking scenes in the film that deserve a lot of credit.

Iron Man reassuring Spider-Man when the latter realizes he’s about to turn into ashes; Star-Lord’s reaction to Gamora’s death, even if that means compromising what appears to be a likely win over Thanos; the moment Thanos realizes he has to sacrifice Gamora; or when Star-Lord decides to pull the trigger on her, are some of them.

The most heart-breaking scene of all takes place, in my opinion, right at the beginning of the movie.

We’ve got Tony Stark, one of the most brilliant minds on Earth, holding a flip phone that has just one number in it, Captain America’s. It’s the phone Steve Rogers sent Tony Stark at the end of Civil War, telling him that the world can always count on him to show up. Here’s that scene, in case you don’t remember:

Think about that for a moment. A man with Stark’s resources has been carrying that flip phone since he received it. He takes that phone everywhere, even when he’s jogging in the park. Even when he’s talking to Pepper Potts about having children. He could memorize the number and redirect it to whatever modern communication device he’d be using in a heartbeat. That way he’d be able to both call Captain America and receive calls from him if needed.

Stark chooses not to ditch the device. He has that phone near him at all times. It’s the only connection with Rogers that he has left, which is probably why he’s holding on to the handset. And think about what that implies. Keeping that phone close and operational, which means remembering to recharge it now and then, is quite an unnecessary hassle for a man who operates some of the most sophisticated technology on Earth.

Stark still doesn’t call Rogers in the movie, although he realizes that he has to. And a part of him probably wants to do it anyway. It’s Bruce Banner who does it, just as Iron Man, Dr. Strange, and Spider-Man are caught into an inter-galactic fight against Ebony Maw (one of the members of the Black Order).

While it’s clear to Rogers that Banner called him just because Stark held on to that phone, Stark will have to wait to get back on Earth to find out whether the Avengers have joined the fight — or if they’re still alive. Not only is Iron Man wounded and stranded on a planet where most of his allies turned to ash in front of him, but he has no idea who’s still alive back home.

The good news for Stark is that Dr. Strange got to tell him, right before he disappeared from existence, that the fight is not over yet. And events are likely progressing according to that one scenario out of more than 14 million possibilities that Dr. Strange saw, in which Thanos is ultimately defeated.

With all that in mind, that’s why I think Stark’s holding on to that stupid phone is actually the most heart-breaking moment of the movie, adding further depth to the character. Yes, it’s also a great trick that ties Infinity War to Civil War.