With 24 hours left before Iris dies, Team Flash learns that there is only one energy source that can power the "Speed Force Bazooka", in the form of a salvaged Dominator technology held at an A.R.G.U.S. facility. Barry and Cisco ask Lyla for it, but she refuses because of her mistrust of Barry due to his creation of Flashpoint. Barry then visits Snart in 1892, when he was travelling with the Legends, and recruits him to help Barry break into A.R.G.U.S. and steal the device. In the process, A.R.G.U.S. agents eventually capture Barry and Snart, but Lyla, seeing the kindness in Barry's actions, allows Barry to take the device. Snart advises Barry to use the goodness in him to defeat Savitar. Tracy decides to join the team. Cisco vibes about his battle with Killer Frost and leaves to fight her. Savitar breaks Wally's leg. Barry uses the "Speed Force Bazooka" on Savitar, but it fails due to Savitar counteracting it with the Philosopher's Stone, which is made out of calcified speed force energy. Savitar then kills Iris and escapes.