Sift Heads World: Act 4: Cold Memories is the fourth game of the Sift Heads World series.
Vinnie with his team went to Santa Cruz, California to kill Anthony Harris - a corrupted cop. In order not to let the corpse being discovered, Shorty (Based on the character you choose, but I think Shorty is the most Protagonist in this act) used a M-21 to kill him and let the corpse falls to the sea.
While they were in the hotel, Shorty received a letter to 'Maéva' (her maiden name). She read it, and found out that it was written by her sister - Claire. Claire got captured by the trafficking gang that Shorty already familiar with. She got treated badly by them, decided to be discreet, and wrote that letter and asked for Shorty's help.
Knowing that the cops were still searching for Vinnie and his team, Shorty used a tranquilizer gun to put the police to sleep in the Airport and get to Russia.
When they arrived at St-Petersburg, Russia, they met Nico - an old friend of Vinnie. He let them use his jeep to move around.
Vinnie and his team went to the Bar, they found Cherry - an old friend of Shory in the stage. In order not to get attention, they went to the hallway to talk to Cherry. Cherry said that Claire followed Shorty's steps and got caught by the trafficking gang. Many girls with Claire were held against their will in an area far away from there and kept very secret. Cherry said there was a cottages in the north of the city and Shorty could find some clues in there. While they were talking, a bouncer (probably a member of the trafficking gang) came and forced Vinnie's team to get out. They defended themself and get out of the bar.
Shorty headed to the cottages Cherry mentioned, took down the henchmen here and didn't find Claire. But she found a GPS that leads to the fortress of the trafficking gang, then the reinforcements arrived. Shorty killed them and headed back to Nico's place.
The location where they kept girls was too far from there, so Vinnie asked Nico to lend them his helicopter. But Nico said he doesn't have the necessary parts, so they went to the Slum Building to get them for him.
They came back, and Vinnie chatted with Kiro to kill time, then they realized that Shorty was gone with the jeep. Vinnie thought that she came to the fortress and find her sister alone, so he asked Nico to lend him and Kiro to come there faster.
While Vinnie and Kiro was in the helicopter going to the fortress, a plane suddenly appeared. Vinnie said he really wanted to test the helicopter's fire power, then he took down the three henchmen with the helicopter's gun. They were survived and used parachutes, Kiro decided to jump off from the helicopter and finish them with his katana, use their parachutes to make his way to the fortress.
The Trafficking Gang's Fortress
When the helicopter landed, Vinnie and his team took down all of the henchmen around the fortress, then they reunited. Shorty went in there and find her sister. After a while of searching, they found Claire was being pointed by the gun of a henchmen. Vinnie challenged the henchmen to fight with him without weapon, and Vinnie won. They rescued Claire, then Shorty hugged her.