Thus he is able to live under water, but must keep his secret from the world.

They had been able to keep their dark secret to themselves.

At first, they had made every effort to keep their secret to themselves.

She kept her secret until the end of the game.

So we're going to keep a few things a little secret.

And they would have to be kept a secret from everyone until then.

Three may keep a secret, if two of them are dead.

The plan works, although she is told to keep her services a secret.

Each was told to keep the news a secret from the others.

Two can keep a secret, if one of them is dead.