The field of cellular calcium signaling has had a curious history. After its discovery ∼120 years ago – it was a revolutionary discovery if ever there was one – it remained, essentially, dormant for decades. Then, ∼50 years ago it started to pick up momentum. First with findings on muscle, and then with a sequel of impressive discoveries that extended to all cell types. All aspects of cell life gradually fell under the spell of calcium, which, it was discovered, masterfully guides cells from origin to death. It was undoubtedly an era of great enthusiasm for calcium as a carrier of signals. But then, findings began to creep in (hesitantly at first and then more and more rapidly) that showed that there was a flip side to the calcium coin. In the end, it became clear that calcium is an ambivalent signaling molecule that is essential for cell life, but also, potentially (and extremely), dangerous for it. Thus, the time has come to look at the darker side of calcium.