A large trunk is displayed. The audience can be enlisted to have it examined; the trunk is then tied up, wrapped with a cover which is buckled on, then tied up again and the knots sealed with wax. A curtain surrounds the trunk; in a few seconds there is a bump, and the curtain is removed, the trunk freed and uncovered, and opened to reveal an assistant.
A variation is to throw a bag, tied and knotted with a string, into the trunk: the assistant appears inside the bag.
The trunk is of course rigged. Half of its bottom is hinged, but is locked into place with a round key. The cover must be such that it can be buckled at the bottom of the trunk, on the side away from the audience.
As soon as the curtain is in place, the assistant sneaks in and tips the trunk on its side (very gently). He unlocks the bottom, pulls the cover out of the way (which is why it must be buckled), gets into the trunk, puts the cover back in place and buckles it, then closes the bottom. (It doesn't need to be relocked as his weight will keep it closed and the cover will prevent this from being discovered). Now he's in the trunk but it's on its side: so he takes a long, strong screw from concealment about his person, pushes it through one of the ventilation holes of the trunk, and turns — so that the screw acts as a jack which will get the trunk right side up. When the performer hears the trunk fall into the correct upright position, he opens up the curtain and goes through the process of opening the trunk to reveal the assistant, who in the meantime has reversed the screw and left it in the trunk. Hey presto!
In the sealed bag variation, the performer ties up the bag and knots the string first. The assistant has concealed about him a bag of the same appearance but which has a couple of slits in its hems. Its string looks the same as the first bag but is slack. The assistant takes the original bag and conceals it about his person: he then gets into the duplicate bag, and sticks his fingers through the slits to draw the string tight.
The setting is very important here as there must be a way for the assistant to get into the area concealed by the curtain.
The trunk must be large enough for the assistant to be able to move easily enough to accomplish all the movements necessary, but not so large as to appear to be concealing anything. The assistant must be very proficient with his movements as they must all be accomplished as fast as possible. In the case of the bag, the assistant can be getting into it during the pause when the curtain is being pulled aside; the performer can delay a little but only a little.
The wax mentioned above can be sealing wax: whatever it is it must be easy to clean off the ropes used to ties the trunk up. Some knots, the apparently most important ones, can be secured with small padlocks with a bit of ingenuity in the tying.
(Houdini and his wife Bess performed a third variation on this trick: Bess was sealed up in the bag to begin with and placed in the trunk; Houdini stepped behind the concealing curtain and when it was pulled aside, Bess was outside and he was in the bag. They became so proficient that they could do the exchange in three seconds! Now of course Bess started to get out of the bag as soon as the trunk was closed and Houdini gave her a couple of seconds before he went behind the curtain, but it was still a most impressive performance. They called this trick the Metamorphosis).