Protagonist, spouse, and Shaun enter Vault 111 with scientist and two other ex-Navy/Marines. Scientist gets trapped and killed in vault door area. Five remaining survivors enter cryo pods to avoid death by overpressure. Protagonist watches as pod containing Shaun and spouse fills up with cryogenic fluid, effectively 'drowning' them prior to stasis kicking in. Protagonist's pod then starts filling up and he/she blacks out. Cut to 208 years later (June 21st 2285), and protagonist wakes up choking on cryogenic fluid as his/her pod empties. They quickly search for something to change into to replace their freezing cold and soaking wet clothes (specialist training on avoiding hypothermia), hence them wearing the rubberised Vault 111 suit upon leaving. The pod containing their spouse and child is no longer inside the vault, and the other two occupied pods are non functioning and now contain skeletons. There is a locked and sealed hatch inside the vault which refuses to open. An audible alarm, as well as flashing lights and a voiced notification lets our protagonist know that there was a system failure inside the vault. After a quick search, they find a 10mm pistol and some ammo, and on the way out they pick up the Pip-Boy. As the blast-doors open above them, the pressure drop causes them to catch their breath. They must now try and find out what happened to their family, starting at their former home which is on the same plot of land as the vault. The Groundskeeper's Log seems to have been last updated by none other than Codsworth, so maybe he knows something about what is going on.
Of course, I could be wrong.